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1
Oza, Neal N. "Engineering Photonic Switches for Quantum Information Processing." Thesis, Northwestern University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3669298.
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In this dissertation, we describe, characterize, and demonstrate the operation of a dual-in, dual-out, all-optical, fiber-based quantum switch. This "cross-bar" switch is particularly useful for applications in quantum information processing because of its low-loss, high-speed, low-noise, and quantum-state-retention properties.
Building upon on our lab's prior development of an ultrafast demultiplexer [1-3] , the new cross-bar switch can be used as a tunable multiplexer and demultiplexer. In addition to this more functional geometry, we present results demonstrating faster performance with a switching window of ≈45 ps, corresponding to >20-GHz switching rates. We show a switching fidelity of >98%, i. e., switched polarization-encoded photonic qubits are virtually identical to unswitched photonic qubits. We also demonstrate the ability to select one channel from a two-channel quantum data stream with the state of the measured (recovered) quantum channel having >96% relative fidelity with the state of that channel transmitted alone. We separate the two channels of the quantum data stream by 155 ps, corresponding to a 6.5-GHz datastream.
Finally, we describe, develop, and demonstrate an application that utilizes the switch's higher-speed, lower-loss, and spatio-temporal-encoding features to perform quantum state tomographies on entangled states in higher-dimensional Hilbert spaces. Since many previous demonstrations show bipartite entanglement of two-level systems, we define "higher" as d > 2 where d represents the dimensionality of a photon. We show that we can generate and measure time-bin-entangled, two-photon, qutrit (d = 3) and ququat (d = 4) states with >85% and >64% fidelity to an ideal maximally entangled state, respectively. Such higher-dimensional states have applications in dense coding [4] , loophole-free tests of nonlocality [5] , simplifying quantum logic gates [6] , and increasing tolerance to noise and loss for quantum information processing [7] .
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Lawrence, Nathaniel. "Engineering photonic and plasmonic light emission enhancement." Thesis, Boston University, 2013. https://hdl.handle.net/2144/11114.
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Thesis (Ph.D.)--Boston UniversitySemiconductor photonic devices are a rapidly maturing technology which currently occupy multi-billion dollar markets in the areas of LED lighting and optical data communication. LEDs currently demonstrate the highest luminous efficiency of any light source for general lighting. Long-haul optical data communication currently forms the backbone of the global communication network. Proper design of light management is required for photonic devices, which can increase the overall efficiency or add new device functionality. In this thesis, novel methods for the control of light propagation and confinement are developed for the use in integrated photonic devices. The first part of this work focuses on the engineering of field confinement within deep subwavelength plasmonic resonators for the enhancement of light-matter interaction. In this section, plasmonic ring nanocavities are shown to form gap plasmon modes confined to the dielectric region between two metal layers. The scattering properties, near-field enhancement and photonic density of states of nanocavity devices are studied using analytic theory and 3D finite difference time domain simulations. Plasmonic ring nanocavities are fabricated and characterized using photoluminescence intensity and decay rate measurements. A 25 times increase in the radiative decay rate of Er:Si02 is demonstrated in nanocavities where light is confined to volumes as small as 0.01(λ/n)^3 . The potential to achieve lasing, due to the enhancement of stimulated emission rate in ring nanocavities, is studied as a route to Si-compatible plasmon-enhanced nanolasers. The second part of this work focuses on the manipulation of light generated in planar semiconductor devices using arrays of dielectric nanopillars. In particular, aperiodic arrays of nanopillars are engineered for omnidirectional light extraction enhancement. Arrays of Er:SiNx nanopillars are fabricated and a ten times increase in light extraction is experimentally demonstrated, while simultaneously controlling far-field radiation patterns in ways not possible with periodic arrays. Additionally, analytical scalar diffraction theory is used to study light propagation from Vogel spiral arrays and demonstrate generation of OAM. Using phase shifting interferometry, the presence of OAM is experimentally verified. The use of Vogel spirals presents a new method for the generation of OAM with applications for secure optical communications.
3
Millar, Ross W. "Strain engineering of Ge/GeSn photonic structures." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/7918/.
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Silicon compatible light sources have been referred to as the \holy grail" for Si photonics. Such devices would give the potential for a range of applications; from optical interconnects on integrated circuits, to cheap optical gas sensing and spectroscopic devices on a Si platform. Whilst numerous heterogeneous integration schemes for integrating III-V lasers with Si wafers are being pursued, it would be far easier and cheaper to use the epitaxial tools already in complementary-metal-oxide-semiconductor (CMOS) lines, where Ge and SiGe chemical vapour deposition is used in a number of advanced technology nodes. Germanium is an effcient absorber, but a poor emitter due to a band-structure which is narrowly indirect, but by only 140 meV. Through the application of strain, or by alloying with Sn, the Ge bandstructure can be engineered to become direct bandgap, making it an effcient light emitter. In this work, silicon nitride stressor technologies, and CMOS compatible processes are used to produce levels of tensile strain in Ge optical micro-cavities where a transition to direct bandgap is predicted. The strain distribution, and the optical emission of a range of Ge optical cavities are analyzed, with an emphasis on the effect of strain distribution on the material band-structure. Peak levels of strain are reported which are higher than that reported in the literature using comparable techniques. Furthermore, these techniques are applied to GeSn epi-layers and demonstrate that highly compressive GeSn alloys grown pseudomorphically on Ge virtual substrates, can be transformed to direct bandgap materials, with emission >3 m wavelength { the longest wavelength emission demonstrated from GeSn alloys. Such emission is modeled to have a good overlap with methane absorption lines, indicating that there is huge potential for the such technologies to be used for low cost, Si compatible gas sensing in the mid-infrared.
4
Simmonds, Richard. "Adaptive optics for microscopy and photonic engineering." Thesis, University of Oxford, 2012. https://ora.ox.ac.uk/objects/uuid:0f1ed5cc-4e21-4ff5-9444-c9be0e3646e4.
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Aberrations affect the operation of optical systems, particularly those designed to work at the diffraction limit. These systems include high-resolution microscopes, widely used for imaging in biology and other areas. Similar problems are encountered in photonic engineering, specifically in laser fabrication systems used for the manufacture of fine structures. The work presented in this thesis covers various aspects of adaptive optics developed for applications in microscopes and laser fabrication. By mathematically modelling a range of idealised fluorescent structures, the effect of different aberrations on their intensity in various microscopes is presented. The effect of random aberrations on the contrast of these different structures is then calculated and the results displayed on idealised images. Images from a two-photon microscope demonstrate the predicted results. The contrast of two structures is compared when imaged first by a conventional microscope and then by the two-photon or confocal sectioning microscopes. The different specimen structures were seen to be affected to varying extents by each aberration mode. In order to correct for aberrations in microscopy and other photonic applications, adaptive elements such as deformable mirrors are incorporated into the optical setups. An important step is to train the deformable mirror so that it produces appropriate mode shapes to apply a phase to optical wavefronts. One such mirror is modelled using the membrane equation to predict the surface shape when an actuator is applied. Each of these influence functions is combined to produce a set of orthogonal mirror modes, which are used to experimentally produce a set of empirical modes in a two-photon microscope. An alternative method of training a deformable mirror from a spatial light modulator is employed. The focal spot of an optical system is imaged to provide a feedback metric for the mirror to replicate the phase pattern on the spatial light modulator. A two-photon microscope with adaptive optics is demonstrated by imaging the brains of Drosophila deep within the bulk, correcting for both system and specimen induced aberrations using the deformable mirror with empirical mirror modes applied. A harmonic generation microscope is also used to image both biological and non-biological specimens whilst performing aberration correction with a deformable mirror. Adaptive optical methods are also applied to a laser fabrication system, by constructing a dual adaptive optics setup to correct for aberrations induced when fabricating deep in the bulk of a substrate. The efficiency and fidelity of fabrication in diamond substrate is shown to be significantly increased as a result of the dual aberration correction. An outstanding problem in microscopy is the effect of spatially variant aberrations. Using measurements from the adaptive microscopes, the extent to which they are present in a range of specimens is quantified. One potential technique to be used to correct for these aberrations is multi-conjugate adaptive optics. Different configurations of a multi-conjugate adaptive optics system are modelled and the improvement on the Strehl ratio of aberrated images quantified for both simulated images and real data. The application of this technique in experimental microscopes is considered.
5
Zhou, Yaling. "Photonic Devices Fabricated with Photonic Area Lithographically Mapped Process." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1233528818.
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Azabi, Y. O. "Spiral photonic crystal fibers." Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/19372/.
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This thesis is concerned with the study of special types of photonic crystal fibers (spiral) and their optical properties. The work is carried out using simulation techniques to obtain the modal field profile and properties for the designs. The method used in solving the Maxwell’s equations is the full vectorial finite element method with the implementation of penalty function and perfectly matched layer. The penalty function is used to eliminate nonphysical solutions. The perfectly matched layer is integrated to absorb rays of light traveling away from the core. These rays are absorbed by the layer and do not reflect back to negatively influence the results. The spiral shapes are implemented in the distribution of the holes in the cladding region of the photonic crystal fiber to determine the photonic crystal fiber properties. Three different spirals have been introduced which are equiangular, Archimedean and Fermat’s spiral. The study of the effective refractive index, effective area and dispersion with varying spiral parameters have been carried out and the results are analyzed to understand the effect of each parameter. The variation of similar parameters in the spirals leads to similar variation in the optical properties under consideration. Furthermore, the equiangular spiral photonic crystal fibers (ES-PCF) have been investigated in two different dimensional scales. The scales are in comparison with the wavelength of operation in the first case when core size is larger than the operating wavelength. In this case the total dispersion of the fiber has slightly higher values than the material dispersion but similar curve and slope. On the other hand, when the core size is comparable with the wavelength of operation, the dispersion is varying significantly with varying the spiral parameters. The effective area can be made very small and therefore the nonlinearity of the fiber very large to facilitate non-linear applications such as super continuum generation. The equiangular spiral photonic crystal fiber has been modified slightly where the position of holes in the third ring are shifted further from the center and their size is much bigger. This manipulation is proposed in an algorithm in this thesis to facilitate the fabrication of ES-PCF using an adaptive stack and draw technique. The design shows similar optical behavior to an ideal spiral and its dispersion has been tailored for supercontinuum generation.
7
Ou, J. Y. "Reconfigurable photonic metamaterials." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/379328/.
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This thesis reports on the development of a new class of switchable nanostructured photonic metamaterials, Reconfigurable Photonic Metamaterials (RPMs). Over the last decade, fascinating material properties including negative refraction, optical magnetism, invisibility, asymmetric transmission, perfect lenses and many more were demonstrated in metamaterials. Inspired by pioneering work on micro-electro mechanical metamaterials for the terahertz and microwave spectral regions with feature sizes from millimeters to tens and hundreds microns, I develop reconfigurable photonic metamaterials for the optical spectral range that have sub-micron meta molecules and nanoscale design features. In particular, for the first time I developed: Novel fabrication processes for manufacturing reconfigurable photonic metamaterials based on the platform of elastic silicon nitride membranes using focused ion beam lithography, film deposition, precise alignment, etching and annealing techniques. These fabrication techniques have allowed the manufacturing of a wide range of reconfigurable metamaterials consisting of bi-layer (gold/silicon nitride) or tri-layer (gold/silicon nitride/gold) structured membranes suitable for applications as plasmonic RPMs. Novel RPMs tunable by ambient temperature that operate in the optical and near infrared parts of the spectrum. With such metamaterials exploiting the change in plasmonic response due to differential thermal expansion in bimorph nanostructures I have demonstrated 50% changes in optical transmission at the wavelength of 1735 nm when the temperature is ramped from 76 K to 270 K. Novel RPMs operating in the near-infrared part of the spectrum that can be controlled by electric signals. These types of metamaterials harness electrostatic forces on the nanoscale and offer up to 20 MHz modulation bandwidth. At a threshold level of stimulation these metamaterials exhibit non-volatile switching with up to 250% transmission change. As a part of this research I developed a characterization technique that allows imaging and recording of the electrostatic switching under a scanning electron microscope. Novel optically controlled RPMs exploiting near-field optical forces induced by light and optical heating for reconfiguration. Such metamaterials show a new type of optomechanical nonlinearity leading to intensity-dependent transmission that exceeds the cubic nonlinearity of GaAs by seven orders of magnitude. Using CW diode lasers operating at telecommunication wavelengths of 1.3 μm and 1.55 μm I have demonstrated cross-wavelength optical modulation with amplitude of about 1 % that can be achieved at only about 1 mW of average power of the control beam. I also developed the numerical analysis of thermo-opto-mechanical properties of the structures and calculated eigenmodes and cooling constants of the RPMs under modulated laser irradiation. Overall, the development of reconfigurable photonic metamaterials provides a new and flexible platform for the control of metamaterial properties "on demand". Such metamaterials can find applications in sensors, tunable spectral filters, switches, modulators, programmable transformation optics devices and any other application where tunable optical properties are required.
8
Grilli, Simonetta. "Ferroelectric domain engineering and characterization for photonic applications." Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4001.
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Scrimgeour, Jan. "Engineering waveguide structures in three-dimensional photonic crystals." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534199.
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Tandon, Sheila (Sheila N. ). 1978. "Engineering light using large area photonic crystal devices." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33931.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references.
Photonic crystals are fabricated structures composed of a periodic arrangement of materials with differing indices of refraction. This research has focused on the realization of two distinct photonic crystal structures in which large area has played a key role: 1) large area broadband saturable Bragg reflectors, and 2) large area 2D photonic crystal devices. Saturable Bragg reflectors (SBRs) can be used to self-start ultra-short pulse generation in a variety of solid state and fiber lasers. To form shorter pulses, SBRs with broadband reflectivity and large area (100's of [mu]m) are required. This thesis describes the design and fabrication of large area broadband saturable Bragg reflectors through the monolithic integration of semiconductor saturable absorbers with large area broadband Bragg mirrors. One of the key elements for realizing this device is the development of a wet oxidation process to create buried low-index ... layers over large areas. Large area 2D photonic crystals enable new methods for routing and guiding light with applications in compact integrated optical circuits. This research has explored the design and fabrication of two large area (centimeter-scale) 2D photonic crystal devices: a superprism and a super- collimator.
(cont.) A superprism is a photonic crystal device in which the direction of light propagation is extremely sensitive to the wavelength and angle of incidence. A super- collimator is a device in which light is guided by the dispersion properties of a photonic crystal slab without boundaries which define the light's path. Design, fabrication, and testing are discussed for both 2D photonic crystal devices.
bu Sheila N. Tandon.
Ph.D.
11
Savov, Emil I. "Multichannel photonic networks." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7835.
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This thesis presents several alternatives for fibre-optic local and metropolitan area networks. The issues considered are mainly related to the physical layer of the networks, i.e., the topology and the optical communications problems. The following approaches were considered in more detail: photonic switching using spatial light modulators; subcarrier-multiplexing techniques using direct optical detection, and in particular the transmission of 64-QAM signals by optical fibre; and subcarrier-multiplexing techniques combined with coherent optical detection. The spatial light modulator appears to be one of the most promising means for building a large-size (e.g., 1000 $\times$ 1000) optical space switch. The main constraints are the attenuation of the optical signal and the crosstalk between the channels. Other problems such as fan-in and fan-out are also addressed. Theoretical and experimental results are presented on the fibre-optic transmission of microwave 64-QAM signals at 90 Mb/s rate. Two important methods of improving the system performance are discussed and demonstrated: laser reflection-induced intensity noise minimization, and error-correction coding using a self-orthogonal convolutional code. The applicability of this transmission technique to the distribution of digital video services is assessed. The concept of photonic networks which use subcarrier-multiplexing techniques together with coherent optical detection is presented. The different radio and optical modulation formats that can be used are investigated and compared for several system modes of operation. The effects of laser phase noise on the system performance are also addressed. An 8-port homodyne phase-diversity receiver is analyzed theoretically.
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Fink, Yoel 1966. "Polymeric photonic crystals." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9291.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2000."February 2000."
Includes bibliographical references (p. 126-129).
Two novel and practical methods for controlling the propagation of light are presented: First. a design criterion that permits truly omnidirectional reflectivity for all polarizations of incident light over a wide selectable range of frequencies is derived and used in fabricating an all dielectric omnidirectional reflector consisting of multilayer films. Because the omnidirectionality criterion is general, it can be used to design omnidirectional reflectors in many frequency ranges of interest. Potential uses depend on the geometry of the system. For example, coating of an enclosure will result in an optical cavity. A hollow tube will produce a low-loss, broadband waveguide, planar film could be used as an efficient radiative heat barrier or collector in thermoelectric devices. A comprehensive framework2 for creating one, two and three dimensional photonic crystals out of self-assembling block copolymers has been formulated. In order to form useful band gaps in the visible regime, periodic dielectric structures made of typical block copolymers need to be modified to obtain appropriate characteristic distances and dielectric constants. Moreover, the absorption and defect concentration must also be ~ontrolled. This affords the opportunity to tap into the large structural repertoire, the flexibility and intrinsic tunability that these self-assembled block copolymer systems offer. A block copolymer was used to achieve a self assembled photonic band gap in the visible regime. By swelling the diblock copolymer with lower molecular weight constituents control over the location of the stop band across the visible regime is achieved, One and three-dimensional crystals have been formed by changing the volume fraction of the swelling media. Methods for incorporating defects of prescribed dimensions into the self-assembled structures have been explored leading to the construction of a self assembled microcavity light-emitting device.
by Yoel Fink.
Ph.D.
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Chen, Kevin M. (Kevin Ming) 1974. "Ordered photonic microstructures." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8785.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2001."February 2001."
Includes bibliographical references (p. 149-157).
This thesis examines novel photonic materials systems possessing order in the atomic, microscopic, and macroscopic dimensional regimes. In the atomic order regime, a structure-property investigation is done for Er203 in which the first report of room temperature photoluminescence (PL) is provided. Thin films of the rare earth oxide were deposited via reactive sputtering of Er metal in an Ar/02 ambient, and subsequently annealed to promote grain growth. Heat treatment consisting of a 650°C followed by 1000°C anneal produces maximum crystallinity as measured by glancing angle x-ray diffraction. These films show characteristic PL at [lambda]=1.54 [mu]m. In the microscopic order regime, omnidirectional reflectors and thin film microcavities are demonstrated using sol-gel and solid-state materials. A first demonstration of omnidirectional reflectivity in sol-gel structures was accomplished using a dielectric stack consisting of 12 spin-on Si02/Ti02 quarterwave sol-gel films. Similarly, solid-state dielectric stacks consisting of 6 Si/Si02 sputtered films were used to demonstrate the same principle. Microcavities were formed using sol-gel structures, producing a low quality factor Q=35 due to limitations in film thickness control and lossy interfaces from stress-induced cracks. The high index contrast Si/Si02 microcavities enabled Q ~1000 using 17 total layers following hydrogenation of dangling bonds within the amorphous Si films. Combining fabrication processes for the solid-state microcavity and Er20 3 films, a device was fabricated to demonstrate photoluminescence enhancement of an Er20 3 film embedded in a microcavity. The structure consisted of 3-bilayer mirrors on either side of an Si02/Er203/Si02 cavity. The Q~300 was near the theoretical value for such a structure. At room temperature, PL of Er20 3 was enhanced by a factor of 1000 in the microcavity compared to a single thin film. In the macroscopic order regime, self-assembly of micron-sized Si02 and polystyrene latex colloidal particles into 2D crystals is presented. The colloidal assemblies offer a relatively easy processing route for fabrication of photonic bandgap structures. Large (> 1 mm diameter) single crystal grains of colloids were formed using controlled evaporation and fluid flow techniques. A novel solution enabling postprocessing of the fragile ordered assemblies is presented in which polyelectrolyte multilayers serve as adsorption platforms that anchor the colloidal assemblies. Tailorability of the polyelectrolyte surface properties (charge density, morphology) enables tuning of the colloid adsorption behavior. The polyelectrolyte surface affects colloid adsorption by influencing its surface diffusion. Observations of colloid surface diffusion were made using optical microscopy. Use of polyelectrolytes patterned via rnicrocontact printing enables fabrication of colloid assemblies containing predesigned point and line defects. The patterned polyelectrolyte adsorption template allows placement of colloids in specific geometric arrangement, making possible the realization of sensors or functional photonic bandgap devices such as waveguides or photon traps. Three mechanisms were used to control· adsorption: (1) pH of the colloid suspension, which determines the ionization of the uppermost surface of the polyelectrolyte multilayer; (2) ionic strength of the suspension, which determines the extent of charge screening about the colloid and polyelectrolyte; and (3) concentration of added surfactant, which causes charge screening and introduces hydrophobic interactions between the surfactant and polyelectrolyte.
by Kevin Ming Chen.
Ph.D.
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Md, Zain Ahmad Rifqi. "One-dimensional photonic crystal / photonic wire cavities based on silicon-on-insulator (SOI)." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/996/.
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It has been of major interest in recent research to produce faster optical processing for many telecommunications applications, as well as other applications of high performance optoelectronics. The combination of one-dimensional photonic crystal structures (PhC) and narrow photonic wire (PhW) waveguides in high refractive-index contrast materials such as silicon-on-insulator (SOI) is one of the main contenders for provision of various compact devices on a single chip. This development is due to the ability of silicon technology to support monolithic integration of optical interconnects and form fully functional photonic devices incorporated into CMOS chips. The high index contrast of the combination of a silicon core with a surrounding cladding of silica and/or air provides strong optical confinement, leading to the realization of more compact structures and small device volumes. In order to obtain a wide range of device functionality, the reduction of propagation losses in narrow wires is equally important, although there are still performance limitations determined by fabrication processes. Compact single-row PhC structures embedded in PhW waveguide micro-cavities could become essential components for wavelength selective devices, especially for possible application in WDM systems. The high quality factor, Q, and confinement of light in a small volume, V, are important for optical signal processing and filtering purposes, implying large Purcell factor values. In this thesis, one-dimensional photonic crystal/photonic wire micro-cavities have been designed and modeled using both 2D and 3D versions of the finite-difference time-domain (FDTD) approach. These devices were fabricated using electron beam lithography (EBL) and reactive ion etching (RIE) for patterning of the silicon layer. The device structures were characterized with TE polarized light, using a tunable laser covering the range from 1480 nm to 1585 nm. Single-row periodic hole-type PhC mirrors consisting of identical and equally spaced holes were embedded in 500 nm wire waveguides. Two PhC hole mirrors were separated with a cavity spacer varying from 400 nm to 500 nm in length to form a micro-cavity. In contrast, several different cavity arrangements were also successfully investigated, - i.e. extended cavity and coupled micro-cavity structures. The experimental results on photonic crystal/photonic wire micro-cavity structures have demonstrated that further enhancement of the quality-factor (Q-factor) - up to approximately 149,000 at wavelengths in the fibre telecommunications range is possible. The Q factor values and the useful transmission levels achieved are due, in particular, to the combination of both tapering within and outside the micro-cavity, with carefully designed hole diameters and non-periodic hole placement within the tapered sections. On the other hand, a large resonance quality factor of approximately 18,500, together with high normalized transmission of 85% through the use of tapering on both sides of the hole-type PhC mirrors that formed the micro-cavity, has been obtained. For the extended cavity case, the multiple resonances excited within the stop band, together with substantial tuning capability of the resonances obtained by varying the cavity length has been demonstrated, together with a Q-factor value of approximately 74,000 at the selected resonance frequency with a normalised transmission of 40%. In addition, the coupled micro-cavity structures considered in this thesis have formed the basic building block for designing multiple cavity structures where the combination of several cavities splits the selected single cavity resonance frequency into a number of resonances that depends directly on the number of cavities used in the design. The coupling strength between the resonators and the Free Spectral Range (FSR) between the split resonance frequencies of the coupled cavity combination were controlled via the use of different numbers of periodic hole structures – and through the use of different aperiodic hole taper arrangements between the two cavities in the middle section of the mirrors.
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Yang, Biao. "Photonic topological metamaterials." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8103/.
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Topology, a mathematical concept associated with global perspectives, was found to represent geometric aspects of physics. To date, various topological phases have been proposed and classified. Among them, topological gapless phases focusing on the degeneracies of energy bands serving as the singularities in the momentum space, attract much attention. Especially in the three-dimension, various topological semimetals have been proposed. With unit topological charge ±1, Weyl degeneracies have laid the foundation. Also, they show loads of exotic properties, such as Fermi arcs and chiral anomalies. Being relied on the band topology theory, topological gapless phases have also been transferred into classic systems, such as photonics, acoustics and mechanics. Here, we experimentally investigated photonic Weyl systems in the photonic continuum media, where electromagnetic intrinsic degrees of freedom play key roles in constructing the state space. Firstly, we researched chiral hyperbolic metamaterials, a type-II Weyl metamaterials, from which we directly observed topological surface-state arcs. Then, we report the discovery of ideal photonic Weyl systems, where helicoid structure of nontrivial surface states has been demonstrated. Finally, we construct photonic Dirac points, through analysing eigen reflection field, we found the correlation of topological charges in momentum and real spaces.
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Zhu, Di S. M. Massachusetts Institute of Technology. "Superconducting nanowire single-photon detectors on aluminum nitride photonic integrated circuits." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108974.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 85-91).
With recent advances in integrated single-photon sources and quantum memories, onchip integration of high-performance single-photon detectors becomes increasingly important. The superconducting nanowire single-photon detector (SNSPD) is the leading single-photon counting technology for quantum information processing. Among various waveguide materials, aluminum nitride (AlN) is a promising candidate because of its exceptionally wide bandgap, and intrinsic piezoelectric and electro-optic properties. In this Master's thesis, we developed a complete fabrication process for making high-performance niobium nitride SNSPDs on AlN, and demonstrated their integration with AlN photonic waveguides. The detectors fabricated on this new substrate material have demonstrated saturated detection efficiency from visible to near-IR, sub-60-ps timing jitter, and ~6 ns reset time. This work will contribute towards building a fully integrated quantum photonic processor.
by Di Zhu.
S.M.
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Lagonigro, Laura. "Engineering electronic and plasmonic materials for novel photonic devices." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/209899/.
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In the last decade well known materials such as metals and silicon have emerged as new materials for photonic applications leading to the growth of two important fields: plasmonics and silicon photonics. This thesis is divided in two parts with part I focusing on plasmonics, and silicon photonics are the target of part II. Novel substrates exploiting plasmonic effects are currently the subject of extensive research in areas such as biological sensing, medicine, optical microscopy and nanophotonics. Here a new class of silver impregnated polycarbonate substrates will be presented. The fabrication process using a supercritical impregnation technique will be described and the substrates morphologically characterised before being tested for Surface Enhanced Raman Spectroscopy and Metal Enhanced Fluorescence. These substrates exhibit an excellent plasmonic response and benefit from being flexible, robust, inexpensive and biocompatible. The demonstrated ability of post processing the nanocomposites provides an additional degree of design control for a wide range of applications. In part II semiconductor modified microstructured optical fibres (MOFs) will be presented. The combination of semiconductor materials within microstructured optical fibres can lead to highly engineerable devices with wide control over both photonic and electronic properties for both linear and non-linear photonic applications. The presented fabrication process consists of a high pressure chemical vapour deposition method which allows for conformal inclusion of materials such as silicon and germanium within the extremely high aspect ratio pores of MOFs. The deposited material is structurally characterised using SEM, TEM and Raman spectroscopy demonstrating good quality amorphous and polycrystalline growth. The project then focuses on investigating the use of these fibres for silicon photonics applications. Loss measurements performed on a range of samples reveal transmission losses potentially compatible with a wide range of non-linear photonic devices
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Trevino, Jacob Timothy. "Engineering aperiodic spiral order for photonic-plasmonic device applications." Thesis, Boston University, 2013. https://hdl.handle.net/2144/11068.
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Thesis (Ph.D.)--Boston UniversityDeterministic arrays of metal (i.e., Au) nanoparticles and dielectric nanopillars (i.e., Si and SiN) arranged in aperiodic spiral geometries (Vogel's spirals) are proposed as a novel platform for engineering enhanced photonic-plasmonic coupling and increased light-matter interaction over broad frequency and angular spectra for planar optical devices. Vogel's spirals lack both translational and orientational symmetry in real space, while displaying continuous circular symmetry (i.e., rotational symmetry of infinite order) in reciprocal Fourier space. The novel regime of "circular multiple light scattering" in finite-size deterministic structures will be investigated. The distinctive geometrical structure of Vogel spirals will be studied by a multifractal analysis, Fourier-Bessel decomposition, and Delaunay tessellation methods, leading to spiral structure optimization for novel localized optical states with broadband fluctuations in their photonic mode density. Experimentally, a number of designed passive and active spiral structures will be fabricated and characterized using dark-field optical spectroscopy, ellipsometry, and Fourier space imaging. Polarization-insensitive planar omnidirectional diffraction will be demonstrated and engineered over a large and controllable range of frequencies. Device applications to enhanced LEDs, novel lasers, and thin-film solar cells with enhanced absorption will be specifically targeted. Additionally, using Vogel spirals we investigate the direct (i.e. free space) generation of optical vortices, with well-defined and controllable values of orbital angular momentum, paving the way to the engineering and control of novel types of phase discontinuities (i.e., phase dislocation loops) in compact, chip-scale optical devices. Finally, we report on the design, modeling, and experimental demonstration of array-enhanced nanoantennas for polarization-controlled multispectral nanofocusing, nanoantennas for resonant near-field optical concentration of radiation to individual nanowires, and aperiodic double resonance surface enhanced Raman scattering substrates.
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Pasquale, Alyssa Joy. "Engineering photonic-plasmonic devices for spectroscopy and sensing applications." Thesis, Boston University, 2012. https://hdl.handle.net/2144/32043.
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Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
The control of light on the nano-scale has driven the development of novel optical devices such as biosensors, antennas and guiding elements. These applications benefit from the distinctive resonant properties of noble metal thin films and nanoparticles. Many optimization parameters exist in order to engineer nanoparticle properties for spectroscopy and sensing applications: for example, the choice of metal, the particle morphology, and the array geometry. By utilizing various designs from simple monomer gratings to more complex engineered arrays, we model and characterize plasmonic arrays for sensing applications. In this thesis, I have focused on the novel paradigm of photonic-plasmonic coupling to design, fabricate, and characterize optimized nanosensors. In particular, nanoplasmonic necklaces, which consist of circular loops of closely spaced gold nanoparticles, are designed using 3D finite-difference time-domain (FDTD) simulations, fabricated with electron-beam lithography, and characterized using dark-field scattering and surface-enhanced Raman spectroscopy (SERS) of p-mercaptoaniline (pMA) monolayers. I show that such necklaces are able to support hybridized dipolar scattering resonances and polarization-controlled electromagnetic hot-spots. In addition, necklaces exhibit strong intensity enhancement when the necklace diameter leads to coupling between the broadband plasmonic resonance and the circular resonator structure of the necklace. Hence, these necklaces lead to stronger field intensity enhancement than nanoparticle monomers and dimers, which are also carefully studied. Furthermore, by embedding a dimer into one or more concentric necklace resonators, I am able to efficiently couple radiation into the dimer hot-spot by utilizing first- and second-order far-field coupling. This nanolensing leads to an order of 6-18 times improvement in Raman enhancement over isolated dimers, which is a promising platform for compact on-chip sensors. Additionally, I have fabricated and experimentally characterized devices that were designed in my group for SERS of pMA using an optimization algorithm. The algorithm confirms that the best arrangement of nanoparticles to increase near-field intensity enhancement in a single hot-spot is to embed a dimer into particles that couple light into the hot-spot via far-field photonic radiation. These genetically optimized nanoantennas show improvement in Raman enhancement 10 times that of nanoparticle dimers, and 100 times the enhancement of optimized two-dimensional monomer diffraction gratings.
2031-01-02
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Urbas, Augustine M. (Augustine Michael) 1974. "Block copolymer photonic crystals." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29977.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2003.Includes bibliographical references (p. 151-162).
This thesis explores the photonic properties of block copolymer systems. One dimensionally periodic dielectric stacks are fabricated with symmetric, lamellar forming, copolymer systems: diblock copolymers, solvent swollen BCP materials, and homopolymer swollen BCP blends. Each system exhibits reflectivity in visible spectrum. These materials are also investigated for their phononic band properties by Brillouin scattering. A copolymer forming the three dimensional double gyroid at optically relevant length scales and its reflective properties are presented as well. Experimental results document the initial observation of photonic optical properties related to the microstructure of a block copolymer. One dimensionally periodic, lamellar polymer block copolymer systems of poly(styrene-b-isoprene) are used to fabricate multilayered optical structures with a range of lamellar dimensions. The lamellar repeat of the copolymer morphology is shown to be adjustable by blending symmetric amounts of like homopolymers of lower molecular weight with the copolymer. The composition of the blends remains symmetric and the morphology is shown to remain lamellar. An isopleth of composition is examined and photonic crystals containing up to 60 wt % homopolymer exhibit wavelength selective reflectivity from the ordered morphology. The wavelength of reflectivity is correlated with the lamellar repeat spacing and morphology. The optical properties of solvent swollen ultrahigh molecular weight block copolymers are examined. The wavelength selective reflectivity is shown to correlate with the expected behavior of the phase segregated morphology. Deformation sensitive ordered gels are fabricated by using a non-volatile, alkyl phthalate plasticizer. The optical properties are shown to respond to the material strain. A simple demonstration of the visualization of the strain field of a deforming system is presented. In addition these gels are shown to exhibit phononic band gap behavior. The system is studied by Brillouin scattering and resonant phonons arising from the morphology are predicted and observed. Three dimensionally periodic photonic crystals formed of a double gyroid styrene- isoprene diblock copolymer are also documented. The copolymer material is considered as formed and also after a series of processing steps.
(cont.) Etching of the isoprene matrix is demonstrated yielding a free standing air-styrene double gyroid. This material is then used to replicate the matrix geometry in titania by infiltration with a sol-gel precursor and subsequent pyrolysis. The structure of the double gyroid material is examined via x-ray scattering and electron microscopy. The photonic band properties of the double gyroid structure for multiple constituent materials with a broad range of refractive indices are examined. Features in optical measurements resulting from the double gyroid structure are observed consistent with the 250nm cubic lattice parameter. A block copolymer photonic crystal platform is outlined and presented. Acousto-optic, phononic crystal properties are noted in these materials and applications are discussed. Strategies for creating a block copolymer based material with an absolute band gap ...
by Augustine M. Urbas.
Ph.D.
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Ye, Erika. "Periodic subwavelength photonic structures." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/111287.
Full textAbstract:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 110-117).
Three applications of the interaction of light with periodic dielectric structures are investigated. The first application is large-area spectroscopy, for which we use the mid-field diffraction pattern generated by the light source passing through a transmission grating to determine its spectral composition. By utilizing a large grating size, we are able to achieve resolutions of < 4 nm experimental while having an etendue of roughly 0.033 mm2. Furthermore, since we are sampling the mid-field light pattern as opposed to the farfield, the entire spectrometer can fit within a 10 mm by 10 mm by 5 mm volume. The second application are barcodes based on the wavelength-dependent back-scattering off of a photonic crystal resonant cavity. The challenge is that we want to observe high quality factor resonant peaks while reducing the size of the crystal to less than 10 microns. So far the highest quality factor observed was about 800. The third application is a Fano silicon photonic crystal modulator waveguide device. The resonant cavity of the modulator is a 1D photonic crystal cavity. If we excite the fundamental and first excited mode of the waveguide, we obtain a Fano resonance that can potentially increase modulation depth and efficiency. We investigated how to improve the modulator architecture to reliably design resonators with sharp Fano resonance peaks. Those these applications are still in their early stages, the are promising for furthering each technology.
by Erika Ye.
M. Eng.
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Sorace, Cheryl M. "Advanced silicon photonic modulators." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62431.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 120-123).
Various electrical and optical schemes used in Mach-Zehnder (MZ) silicon plasma dispersion effect modulators are explored. A rib waveguide reverse biased silicon diode modulator is designed, tested and found to operate at speeds up to 13 GHz with a V"L of 1.2 Vcm. MOS capacitor modulator designs are investigated as an alternative, but are not found to offer significant advantages. Modulators are also designed for fabrication in an actual CMOS process -a crucial step in the quest for low-cost integration with modern electronic devices. Photonic crystal structures, which promise smaller footprint sizes and lower power requirements, are also investigated, but it proves difficult to obtain a physically feasible design. Finally, a linearization scheme for Mach-Zehnder modulators is proposed to significantly improve signal fidelity in analog applications. Simulations are used to demonstrate the effectiveness of this scheme for reverse biased silicon diode modulators.
by Cheryl M. Sorace.
S.M.
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Atkin, Dale Mark. "Photonic crystals in planar waveguides." Thesis, University of Southampton, 1998. https://eprints.soton.ac.uk/394394/.
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In this thesis the properties of waveguide modes in photonic crystal planar waveguides are considered. These are waveguides that have been etched with multi-dimensional gratings to create new wavelength dispersive and spatially dispersive behaviours. Analytical models have been developed for the modes in one and two-dimensional photonic crystal waveguides. These describe many of the rich phenomena that may be observed. Weak two-dimensional photonic crystal planar waveguides have been fabricated and their properties have been measured with a specially developed conical prism coupling technique. This thesis demonstrates the advantages of combining photonic crystals with planar waveguides. While future lithographic systems will have sufficient resolution to incorporate photonic crystal regions in integrated optical devices, it has been shown that the waveguide geometry increases the actual grating period required for optical band gaps and so lessens technological difficulties. It is also shown that there are stationary modes which could act as microresonators and that ranges of modes can be suppressed in multimode waveguides. Prism coupling has demonstrated the strong dispersive and frequency selective behaviour of weak photonic crystal waveguides. The future application of this work to efficient, broadband, nonlinear wavelength conversion is proposed.
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Choi, Hyeongrak. "Photonic crystal cavity with self-similar structure and single-photon Kerr nonlinearities." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108985.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 31-34).
We propose a design of photonic crystal cavity with self-similar electromagnetic boundary conditions, that achieve ultrasmall mode volume (Vff). The electric energy density of a cavity mode can be maximized in the air or dielectric region, depending on the choice of boundary conditions. We illustrate the design concept with a silicon-air ID photon crystal cavity that reaches an ultrasmall mode volume of Vff ~ 7.01 x 10- 5 [lambda]3 at [lambda] ~ 1550 nm. We show that the extreme light concentration in our design can enable ultra-strong Kerr nonlinearities, even at the single photon level. These features open new directions in cavity quantum electrodynamics, spectroscopy, and quantum nonlinear optics.
by Hyeongrak Choi.
S.M.
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Klitis, Charalambos. "Polarisation selective integrated silicon photonic devices." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/8725/.
Full textAbstract:
The main objective of this thesis was the development of polarisation selective gratings in silicon-on-insulator (SOI) technology. These devices can find numerous applications in the design of highly performing optical filters and, more in general, in all those devices that require on-chip manipulation of the polarisation state. The development of these devices was preceded by the optimisation of several fabrication processes, such as lithography and dry etching, and the re-design of a number of key components such as inverse polymer tapers and metallic heaters for thermal tuning. This activity culminated into a very robust process flow for SOI devices, with repeatable propagation losses in the order of 1 dB/cm, heaters with a very high tuning efficiency of 12 mW per π phase shift and 2dB and 1dB waveguide-to-optical fibre coupling losses for the TE and TM polarised mode, respectively. The grating designs developed in this thesis consisted of periodic holes etched onto the top surface of the silicon optical waveguide. Such geometry overlaps strongly with the TM polarised mode only and does not introduce additional losses to the TE mode. The benefit and the additional functionalities provided by the top grating geometry was assessed on two different polarisation sensitive devices. The first consisted in a microring resonator with integrated gratings for the emission of optical vortex beams, for which the top gratings provided a route to engineer the polarisation state of the emitted beam. The second device was a Bragg grating filter, where the top grating allowed the demonstration of extinction ratio values as high as 60dB by filtering the residual TM mode generated by the strong polarisation scattering.
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Settaluri, Krishna Tej. "Photonic Links| From Theory to Automated Design." Thesis, University of California, Berkeley, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13423776.
Full textAbstract:
Recent advancements in silicon photonics show great promise in meeting the high bandwidth and low energy demands of emerging applications. However, a key gating factor in ensuring this necessity is met is the utilization of a link design methodology which transcends the various levels in the hierarchy, ranging from the device and platform level up to the systems level. In this dissertation, a comprehensive methodology for link design will be introduced which takes a two-prong approach to tackling the issue of silicon photonic link efficiency. Namely, a fundamentals-based first principles approach to link optimization will be introduced and validated. In addition, physical design trade-offs connecting levels in the architectural hierarchy will also be studied and explored. This culminates in an intermediate goal of this dissertation, which is the first-ever design and verification of a full silicon photonic interconnect on a 3D integrated electronic-photonic platform. To proceed and further enable the rapid exploration of the link design architectural space, the analog macros for a majority of this dissertation were auto-generated using the Berkeley Analog Generator (BAG). With these key design tools and framework, performance bottlenecks and improvements for silicon photonic links will be analyzed and, from this analysis, the motivation for a new, single comparator-based PAM4 receiver architecture shall emerge. This architecture not only showcases the tight bond in dependency between high-level link specifications and low level device parameters, but also shows the importance of physical design constraints alongside fundamental theory in influencing end-to-end link performance.
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Hart, Shandon D. (Shandon Dee) 1978. "Multilayer composite photonic bandgap fibers." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32264.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.Includes bibliographical references (leaves 120-126).
Materials and fabrication techniques are developed that lead to the successful fabrication of multilayer composite photonic bandgap fibers. The pertinent background in electromagnetic theory of multilayer dielectric mirrors and optical fibers is surveyed. Materials properties constraints are outlined, with emphasis on those constraints related to processing strategy and ultimate target length scale. Interfacial energy is measured in a chalcogenide glass / organic polymer composite system selected for fiber fabrication. A classical capillary instability model is employed to predict the feasibility of fiber fabrication based on material properties; from this model, quantitative materials selection criteria related to ultimate length scale are derived. Good agreement is found between the calculated materials selection criteria and controlled fiber experiments. The fiber fabrication techniques are described and analyzed; chalcogenide film deposition is characterized using Raman and electron microprobe spectroscopy, and heat transfer during fiber drawing is modeled using a commercial finite-element software package. The developed materials and fabrication processes are used to perform two case studies in novel photonic bandgap fiber fabrication; the first case study deals with externally reflecting omnidirectional 'mirror-fibers', while the second deals with hollow- core light transmitting fibers. The reflecting mirror-fibers consist of a tough polymer core surrounded by multiple coaxial submicron-thick layers of a high-refractive-index glass and a low-index polymer; these layers reflect external light from all incident angles and polarizations in the mid-IR range.
(cont.) Large directional photonic gaps and high reflection efficiencies that are comparable to the best metallic reflectors were measured. In the second case study, the light-transmitting fibers consist of a hollow air core surrounded by multiple alternating layers of the same materials, resulting in large infrared photonic bandgaps. Optical energy is strongly confined in the hollow fiber core, enabling light guidance in the fundamental and up to fourth-order gaps. These gaps are placed at selectable wavelengths within a large selection range, from 0.75 to 10.6 m. Tens of meters of hollow photonic bandgap fibers designed for 10.6 pgm radiation transmission are fabricated. We demonstrate transmission of carbon dioxide (CO2) laser light with high power-density through more than 4 meters of hollow fiber and measure the losses to be less than 1.0 dB/m at 10.6 microns. Thus, fiber waveguide losses are suppressed by orders of magnitude compared to the intrinsic fiber material losses.
by Shandon D. Hart.
Ph.D.
28
Tong, Jonathan Kien-Kwok. "Photonic engineering of near- and far-field radiative heat transfer." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104127.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 181-195).
Radiative heat transfer is the process by which two objects exchange thermal energy through the emission and absorption of electromagnetic waves. It is one of nature's key fundamental processes and is ubiquitous in all facets of daily life from the light we receive from the Sun to the heat we feel when we place our hands near a fire. Fundamentally, radiative heat transfer is governed by the photonic dispersion, which describes all the electromagnetic states that can exist within a system. It can be modified by the material, the shape, and the environment. In this thesis, morphological effects are used to modify the photonic dispersion in order to explore alternative methods to spectrally shape, tune, and enhance radiative heat transfer from the near-field to the far-field regimes. We start by investigating the application of thin-film morphologies to different types of materials in the near-field regime using a rigorous fluctuational electrodynamics formalism. For thin-film semiconductors, trapped waveguide modes are formed, which simultaneously enhance radiative transfer at high frequencies where these modes are resonant and suppress radiative transfer at low frequencies where no modes are supported. This spectrally selective behavior is applied to a theoretical thermophotovoltaics (TPV) system where it is predicted the energy conversion efficiency can be improved. In contrast, thin-films of metals supporting surface plasmon polariton (SPP) modes will exhibit the opposite effect where the hybridization of SPP modes on both sides of the film will lead to a spectrally broadened resonant mode that can enhance near-field radiative transfer by over an order of magnitude across the infrared wavelength range. In order to observe these morphological spectral effects, suitable experimental techniques are needed that are capable of characterizing the spectral properties of near-field radiative heat transfer. To this end, we developed an experimental technique that consists of using a high index prism in an inverse Otto configuration to bridge the momentum mismatch between evanescent near-field radiative modes and propagation in free space in conjunction with a Fourier transform infrared (FTIR) spectrometer. Preliminary experimental results indicate that this method can be used to measure quantitative, gap-dependent near-field radiative heat transfer spectrally. While utilizing near-field radiative transfer remains a technologically challenging regime for practical application, morphological effects can still be used to modify the optical properties of materials in the far-field regime. As an example, we use polyethylene fibers to design an infrared transparent, visibly opaque fabric (ITVOF), which can provide personal cooling by allowing thermal radiation emitted by the human body to directly transmit to the surrounding environments while remaining visible opaque to the human eye.
by Jonathan Kien-Kwok Tong.
Ph. D.
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Najafi, Faraz. "Superconducting nanowire single-photon detectors : new detector architectures and integration with photonic chips." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99836.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 153-161).
Superconducting nanowire single-photon detectors (SNSPDs) are a promising technology for long-distance optical communication and quantum information processing. Recent advances in single-photon generation, storage and detection technologies have spurred interest in integration of these components onto a single microchip, which would act as a low-power non-classical optical processor. In this thesis, I will present a method for the scalable integration of SNSPDs with photonic chips. I will show that, using a micron-scale flip-chip process, waveguide-coupled SNSPDs can be integrated onto a variety of material systems with high yield. This technology enabled the assembly of the first photonic chip with multiple adjacent SNSPDs with average system detection efficiencies beyond 10%. Using this prototype, we will show the first on-chip detection of non-classical light. I will further demonstrate optimizations to the detector design and fabrication processes. These optimizations increased the direct fabrication yield and improved the timing jitter to 24 ps for detectors with high internal efficiency. Furthermore, I will show a novel single-photon detector design that may have the potential to reach photodetection dead times below 1ns.
by Faraz Najafi.
Ph. D.
30
Leu, Jonathan Chung. "Integrated silicon photonic circuit simulation." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120431.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 97-111).
Integrated silicon photonics is an exciting emerging technology, utilizing the high bandwidth and high timing resolution that optics provides in many applications. To maximize the benefits of these optical-electrical systems, tight integration of the electronic and photonic components are necessary. In light of this need, we've developed a Cadence toolkit library written in VerilogA that simulates both the amplitude and phase of optical signals, as well as optical-electrical interactions. The runtime is greatly improved by simulating the optical signal relative to a reference frequency, which is chosen to be close to the frequency range of interest. We have identified a set of fundamental photonic components, and described each at the physical level, such that the characteristics of a composite device will be created organically. We show that the simulated results match analytic solutions for simple devices like resonant ring filters and more complicated devices like single sideband modulators. Adding to this toolkit library, we then discuss devices that are required for handling more special cases, such as chromatic dispersion in the waveguide, and non-ideal optoelectronic devices. Finally, we demonstrate simulations of complicated systems such as WDM links and Pound-Drever-Hall loops. This will allow designers to unify our photonic device designing and modeling environment with circuit and system level design, giving us greater insight on the trade-offs that take place between the two realms.
by Jonathan Leu.
Ph. D.
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Uthman, Muhammad. "Finite element characterisation of photonic crystal fibres." Thesis, City University London, 2013. http://openaccess.city.ac.uk/3012/.
Full textAbstract:
Rigorous numerical simulations have been carried out by using the Finite Element Method (FEM) in order to calculate bending and leakage losses of Photonic Crystal Fibres (PCF). A modal solution approach including the implementations of the conformal transformation and the Perfectly Matched Layer (PML) were undertaken to determine the bending and leakage losses of several designs of Photonic Crystal Fibres. This was carried out by varying key parameters such as the pitch (Λ), diameter (d) and air-filling fraction (d/Λ). Output modal parameters including the effective indices, spot sizes, leakage and bending losses as well as the mode field profiles were obtained. These output parameters were obtained by varying the bending radius (R) from very large values to very low values for different dimensions of the PCF, with results being obtained for Transverse Magnetic and Transverse Electric (quasi-TM and quasi-TE) polarizations. These parameters were calculated by solving the Maxwell’s equations using the H-field vector formulation and with the inclusion of PML to solve complex eigenvalue equations. Generally, it was observed that for all Λ, d/Λ and the polarization considered, as R is reduced from a very high value to lower values, the bending losses increase and there is a sharp increase at some lower values of R. At some very low values of R, some oscillatory behaviour was observed in the curves obtained for the fibre losses, where further investigations were carried out. These oscillations appeared due to degeneration of the fundamental mode with the cladding modes. In most of the cases investigated, there was a correlation in the variation of effective indices the loss values and also in the variation of spot sizes. PCFs with non-identical air-holes were also investigated in which case the d ≠ d2 (diameter of 4 larger air-holes in the first ring) and knowing the values for TM and TE polarizations, it was possible to determine the birefringence, which is the difference between the effective indices for the TM and TE modes and also the loss ratio, which is the ratio of TM loss to that of the TE loss. All the input and output parameters that were considered with the symmetric air-holes were also considered in the case with fibre with asymmetric air-holes study. The results obtained are very important in the design of Single Mode Single Polarization PCF. Results have also been obtained from the studies done of asymmetric arrangement of air-holes which lead to the design of Single Mode Single Polarization PCF. Work was carried out on the design of a tapered PCF that could be efficiently coupled to a single mode fibre, SMF. This was achieved by increasing the number rings up to 10 rings of air-holes in the cladding and having the outermost ring with larger air-holes, the inner rings were near cutoff. This fibre was coupled to a conventional SMF to allow for better tolerance to fabrication errors. There has also been work carried out in polymer fibre namely Teflon and TOPAS in the terahertz regime. The conventional hexagonal arrangement of PCF was simulated and compared to spiral PCF in THz. An improved PCF design having a porous core with hexagonal arrangement and cladding was designed and analysed and low-loss guidance in THz was achieved. Thus overall a number of different PCF designs were considered and their properties evaluated and detailed knowledge has been obtained on potential performance of such fibres.
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Kabir, Saiful. "Finite element modelling of photonic crystal fibres." Thesis, City University London, 2007. http://openaccess.city.ac.uk/8592/.
Full textAbstract:
Photonic crystal fibre (PCF), a new kind of optical fibre, has many air-holes in their cross-section and has potential applications to new optical communication systems. The main objective of this research is the modelling of photonic crystal fibre to identify the fundamental and higher order quasi-TE and TM modes with square, ,rectangular and circular air holes in a square and hexagonal matrix, by using a rigorous full-vectorial H-field based finite element method (FEM). Besides the modal solutions of the effective indices, mode field profiles, spot sizes, modal hybridness, polarization beat length and group velocity dispersion values for equal and unequal air holes; research was carried out to optimize and design highly birefringent PCF. The variation of modal birefringence is shown through the effect of hole diameters, air hole arrangement, structural asymmetry, operating wavelength, and pitch-distance. Birefringence was enhanced by breaking the structural symmetry and this was verified by using unequal air holes. The diameter of two air holes and four air holes in the first ring was changed to break the rotational symmetry and a comparison between the two designs is made in this work. In this work, highly birefringent PCF is designed with higher operating wavelength, larger d2/A value, lower pitch length for a given structural asymmetry. It is identified that birefringence value increases rapidly when d2 is much larger than d. At lower pitch value, one of the highest birefringence values reported so far at wavelertgth of 1.55 J.Jm for an asymmetric PCF using circular air holes. A single polarization guide PCF structure is also achieved. In this study, it has been identified that for fixed d/A and d2/A value, as operating wavelength is increased, birefringence increases significantly. It can also be identified that for higher d/A values, birefringence changes rapidly with A as their corresponding cutoff condition also approaches. One important validation of this work is the existence of modal birefringence for PCF with six-fold rotational symmetry. It is shown that birefringence value of a simple PCF incorporating circular holes but of different diameters is high compared to polarization maintaining Panda or Bow-tie fibres. This research also aims to investigate the modal leakage losses of PCF, by using a semi-vectorial beam propagation method (BPM) based on the versatile FEM. The robust perfectly matched layer (PML) boundary condition has been introduced to the modal solution approach. The effects of d2/A, operating wavelength and number of air holes have been thoroughly detailed and explained. In this study, it has been identified that the confinement loss decreases significantly with the increased number of rings, lower operating wavelength and lower d2/A value. For special case, PCF with large spot-size provides higher leakage loss.
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Stewart, Justin William. "Photonic Crystal-Based Flow Cytometry." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5396.
Full textAbstract:
Photonic crystals serve as powerful building blocks for the development of lab-on-chip devices. Currently they are used for a wide range of miniaturized optical components such as extremely compact waveguides to refractive-index based optical sensors. Here we propose a new technique for analyzing and characterizing cells through the design of a micro-flow cytometer using photonic crystals. While lab scale flow cytometers have been critical to many developments in cellular biology they are not portable, difficult to use and relatively expensive. By making a miniature sensor capable of replicating the same functionality as the large scale units with photonic crystals, we hope to produce a device that can be easily integrated into a lab-on-chip and inexpensively mass produced for use outside of the lab.
Using specialized FDTD software, the proposed technique has been studied, and multiple important flow cytometry functions have been established. As individual cells flow near the crystal surface, transmission of light through the photonic crystal is influenced accordingly. By analyzing the resulting changes in transmission, information such as cell counting and shape characterization have been demonstrated. Furthermore, correlations for simultaneously determining the size and refractive indices of cells has been shown by applying the statistical concepts of central moments.
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Cao, Wei-Wei. "Metropolitan area network using photonic switching." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6665.
Full textAbstract:
The high-bandwidth characteristic has made fiber optics very attractive for metropolitan area network (MAN) implementation. This paper describes the architecture and performance of an integrated fiber optics MAN called TreeNet. The upper level of the TreeNet consists of a tree and the lower level consists of linear buses. Stations are connected to the linear buses via passive taps while branches of the tree are interconnected using passive couplers. Active nodes are used between the two levels for traffic filtering. A Wavelength Division Multiplexing (WDM) multihop architecture, ShuffleNet, is used for this TreeNet. Three hierarchical design models are proposed: (1) ShuffleNet in the upper level and Synchronous Time Division Multiplexing (STDM) in the lower level, (2) ShuffleNets in both upper and lower levels with dedicated channels between stations and the active nodes, (3) same as (2) except there are no dedicated channels. The performances of networks based on these three proposals are evaluated and discussed.
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Khetani, Altaf. "Photonic crystal fiber as a biosensor." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27596.
Full textAbstract:
With the era of technological change at its all time high, advancements in the field of photonics offer us a wide range of innovative potential applications. Over the years photonics has played an important role in modern industries such as telecommunication, sensors and medical imaging. One of the fields which has received a lot of attention is Photonic Crystal Fibers (PCF) for biosensor application. Photonic crystal fiber is a unique type of optical fiber in which continuous channels of (typically) air run their entire length. These 'holes' serve to both confine electromagnetic waves within the core of the fiber and to tailor its transmission properties. The classification of photonic crystal fiber can be solid core PCF where the light is guided by total internal reflection, and Hollow core photonic bandgap fibers (PBF) in which light is guided through the photonic bandgap effect. Simulation of PCF has been done through commercial software known as COMSOL which follows the finite element approach.
The focus of this thesis is on the application of PCF for different sensing applications. Traditionally, solid core PCF has been used for sensing purposes as the cladding channels can be filled with gas or liquid, thus serving as an efficient type of evanescent wave sensing. Hollow core PBF offers huge improvements as the interaction between light and matter is increased by the presence of sample in the core where most of the light is confined.
Conventionally, HC-PBF is used for sensor purposes by selectively filling the core. Here we have used a non-selective filling technique wherein all the channels of PCF are being filled with samples. When the fiber is empty it guides a particular band, and upon filling with other samples, the bandgap is shifted, and depending on this shift one can determine the refractive index of the sample. This type of sensor has been able to detect as low as 10 -5 change in refractive index just by taking a few centimeters of HC-PBF.
Laser Flash Photolysis is one of the leading methods used in photochemistry to determine the transient species such as radicals, excited states or ions, in chemical and biological systems. By using HC-PBF we have replaced the conventional technique of LFP where in a test-tube is used to hold the sample. The sample is excited through a laser and a monitoring beam is used to observe the amount of absorption. The sample required here is on the order of a milliliter which can be scaled down to pico liter by the use of PCF. The LFP results using PCF showed signal enhancement of at least an order of magnitude for samples like xanthone in toluene, xanthone in acetonitryl and water soluble benzoin in methyl viologen.
Raman Spectroscopy is yet another area which had a surge of growth for label free detection of samples. One of the reasons for its popularity is that it provides a unique optical fingerprint of chemicals and biomolecules. In this thesis we have focused on developing HC-PBF for enhancing the Raman signal from the sample. We have obtained an enhancement of over 40 times when using a HC-PBF with a length of 9.5cm. We have also used HC-PBF to study the enhancement of Raman signal from colloidal nanoparticles in an aqueous solution.
Supercontinuum generation is yet another area which has seen tremendous growth through the use of solid core PCF. Here we have covered the excitation of cladding and core mode in an endlessly single mode PCF which has the potential to be used as an effective type of biosensor as the penetration of light in the cladding channels is very strong compared to an evanescent wave field.
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Khorshidahmad, Amin. "Controlling light with slab photonic crystal." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104667.
Full textAbstract:
This thesis presents novel designs and schemes for wavelength demultiplexing, frequency conversion and multi-wavelength generation applications, achieved by engineering the band structure and dynamic control of the dispersion in planar photonic crystal (PhC) platform. The composite superprism demultiplexer, whereby simultaneous diffraction compensation and angular channel separation considerably reduces the footprint required in conventional superprisms, is proposed. A design model is developed and applied to optimize and analyze the scaling properties of the demultiplexer. Expanding the bandwidth of the conventional superprism in a compact stratified hetero-lattice operating in reflective scheme is also investigated. Increasing the adiabatically achievable frequency shift by the structural change induced via tuning the slab refractive index of a nested cavity is shown. Wavelength conversion using the proposed dynamically reconfigurable nested resonators is further studied. In this scheme, ultrafast modulation of the refractive index, e.g. via induced free carriers, transforms the photons stored within the original cavity into the distinct set of eigenmodes of a dynamically formed resonator. As a result, an arbitrary frequency shift, determined by the spectral separation of the resonances of the initial and the tuned cavities, is achievable provided a fast enough tuning. This scheme may also eliminate the adiabatic frequency conversion that normally co-exists with intermodal transitions in a static cavity. Optical comb sources with tunable spectrum by dynamically controlling the reconfiguration, tailoring the dispersion and utilizing the symmetry of the mode profiles in nested resonators is also proposed and numerically demonstrated.Cette thèse présente des concepts et plans originaux pour des applications en démultiplexage de longueur d'onde, conversion de fréquence et génération de multi-longueur d'onde, obtenue par la conception de la structure de bande et le contrôle dynamique de la dispersion de la plate-forme de cristaux photoniques (CPh) planaires.Un démultiplexeur superprisme composite, par lequel la compensation de la diffraction ainsi que la séparation angulaire des canaux réduit considérablement l'encombrement requis par les superprismes classiques, est proposé. Un modèle de conception est développé et appliqué afin d'optimiser et d'analyser les propriétés de mise à l'échelle du démultiplexeur. L'élargissement de la bande passante du superprisme classique dans une exploitation compacte hétéro-réseau stratifiée dans un schéma de réflexion est également étudiée. L'augmentation du décalage de fréquence adiabatique réalisable par le changement structurel qui est induit par la modification de l'indice de réfraction de la dalle dans une cavité imbriquée est présenté. De plus, la conversion de longueur d'onde grâce aux résonateurs imbriqués et dynamiquement reconfigurables qui sont proposés dans cette thèse est étudiée. Dans ce schéma, la modulation ultra-rapide de l'indice de réfraction, par exemple via des porteurs libres induits, transforme les photons accumulés dans la cavité d'origine en un ensemble distinct de modes propres d'un résonateur configuré dynamiquement. En conséquence, un décalage en fréquence arbitraire, déterminé par la séparation spectrale des résonances de la cavité initiale et celles du résonateur accordé, est réalisable à condition qu'un réglage soit fait rapidement. Ce système peut aussi éliminer la conversion de fréquence adiabatique qui accompagne normalement la transition entre les modes dans une cavité statique. La conception de sources peigne de fréquences optiques à spectres accordables par le contrôle dynamique de la configuration, l'adaptation de la dispersion et l'utilisation de la symétrie des profils des modes dans les résonateurs imbriqués est également proposée et démontrée numériquement.
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Kaiser, Florian. "Photonic entanglement engineering for quantum information applications and fundamental quantum optics." Nice, 2012. https://tel.archives-ouvertes.fr/tel-00777002.
Full textAbstract:
Le but de cette thèse est de développer des sources d’intrication photonique pour étudier les réseaux de communication quantique et l’optique quantique fondamentale. Trois sources très performantes sont construites uniquement autour de composants standards de l’optique intégrée et des télécommunications optiques. La première source génère de l’intrication en polarisation via une séparation déterministe des paires de photons dans deux canaux adjacents des télécommunications. Cette source est donc naturellement adaptée à la cryptographie quantique dans les réseaux à multiplexage en longueurs d’ondes. La seconde source génère, pour la première fois, de l’intrication en time-bins croisés, autorisant l'implémentation de crypto-systèmes quantiques à base d’analyseurs passifs uniquement. La troisième source génère, avec une efficacité record, de l’intrication en polarisation via un convertisseur d’observable temps/polarisation. La bande spectrale des photons peut être choisie sur plus de cinq ordres de grandeur (25 MHz - 4 THz), rendant la source compatible avec toute une variété d’applications avancées, telles que la cryptographie, les relais et les mémoires quantiques. Par ailleurs, cette source est utilisée pour revisiter la notion de Bohr sur la complémentarité des photons uniques en employant un interféromètre de Mach-Zehnder dont la lame séparatrice de sortie se trouve dans une superposition quantique d’être à la fois présente et absente. Enfin, pour adapter la longueur d’onde des paires des photons télécoms intriqués vers les longueurs d’ondes d’absorption des mémoires quantiques actuelles, un convertisseur cohérent de longueur d’onde est présenté et discutéThe aim of this thesis is to develop sources of photonic entanglement to study both quantum networking tasks and some of the foundations of quantum physics. To this end, three high-performance sources are developed, each of them taking extensively advantage of standard telecom fibre optics components. The first source generates polarization entanglement via deterministic pair separation in two adjacent telecommunication channels. This source is naturally suitable for quantum cryptography in wavelength multiplexed network structures. The second source generates for the first time a cross time-bin entangled bi-photon state which allows for quantum key distribution tasks using only passive analyzers. The third source generates, with a record efficiency, polarization entanglement using an energy-time to polarization entanglement transcriber. The photon spectral bandwidth can be chosen over more than five orders of magnitude (25 MHz - 4 THz). This permits implementing the source into existing telecom networks, but also in advanced quantum relay and quantum memory applications. Moreover, this source is used to revisit Bohr’s single-photon wave-particle complementarity notion via employing a Mach-Zehnder interferometer with an output quantum beam-splitter in a true superposition of being present and absent. Finally, to adapt the wavelength of the entangled telecom photon pairs to the absorption wavelength of current quantum memories, a coherent wavelength converter is presented and discussed
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Nedeljkovic, Milos. "Silicon photonic modulators for the mid-infrared." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/365498/.
Full textAbstract:
Mid-infrared group-IV material photonics is an emerging field, which aims to migrate techniques used for near-infrared silicon photonics to longer wavelengths, and to address applications in areas such as environmental and bio-chemical sensing, homeland security, telecommunications, medicine or astronomy. In order to create mid-infrared photonic systems, components such as waveguides, splitters/couplers, filters, interferometers and modulators are required. Silicon-on-insulator (SOI) waveguides, which are used in the near-infrared, have high absorption at wavelengths greater than 4μm, and therefore new material platforms will be required for some parts of the mid-infrared. In this project silicon-on-insulator waveguides operating at 3.8μm have been demonstrated with losses as low as 2.0dB/cm. Poly-Si on SOI waveguides, which can be fabricated in a commercial foundry, and germanium on silicon waveguides, which could be used throughout most of the mid-infrared, were also demonstrated at 3.8μm. The passive components required to make a modulator in the SOI material platform were designed, fabricated and characterised. SOI MMIs were demonstrated at 3.8μm with insertion losses as low as 0.10±0.01dB, which is comparable to the best achieved near-IR silicon photonic MMI performance, and Mach-Zehnder interferometers were measured to have insertion losses of 1.3-2.2dB, and extinction ratios of up to 28dB. These components were used to create thermo-optic modulators in SOI, which are the first group-IV waveguide integrated modulators at wavelengths above 3μm. Switching powers as low as 47mW, and a -3dB bandwidth of 23.8kHz, were achieved. In order to build faster modulators, the free-carrier plasma dispersion effect could be employed. However, accurate equations for prediction of this effect in the mid-infrared have not been available until now. A semi-empirical approach has been used to calculate design equations relating the change in absorption coefficient and change in refractive index to change in charge carrier concentration in silicon for wavelengths in the 1.3-14μm wavelength range.
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Sun, Chen Ph D. Massachusetts Institute of Technology. "Design space exploration of photonic interconnects." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68509.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 109-113).
As processors scale deep into the multi-core and many-core regimes, bandwidth and energy-efficiency of the on-die interconnect network have become paramount design issues. Recognizing potential limits of electrical interconnects, emerging nanophotonic integration has been recently proposed as a potential technology option for both on-chip and chip-to-chip applications. As optical links avoid the capacitive, resistive and signal integrity limits imposed upon electrical interconnects, the introduction of integrated photonics allows for efficient realization of physical connectivity that are costly to accomplish electrically. While many recent works have since cited the potential benefits of optics, inherent design tradeoffs of photonic datapath and backend components remain relatively unknown at the system-level. This thesis develops insights regarding the behavior of electrical and hybrid optoelectrical networks and systems. We present power and area models that capture the behavior of electrical interface circuits and their interactions with optical devices. To animate these models in the context of a full system, we contribute DSENT, a novel physical modeling framework capable of estimating the costs of generalized digital electronics, mixed-signal interface circuitry, and optical links. With DSENT, we enable fast power and area evaluation of entire networks to connect the dynamics of an underlying photonics interconnect to that of an otherwise electrical system. Using our methodolody, we perform a technology-driven design space exploration of intra-chip networks and highlight the importance of thermal tuning and parasitic receiver capacitances in network power consumption. We show that the performance gains enabled by photonics-inspired architectures can enable savings in total system energy even if the network is more costly. Finally, we propose a photonically interconnected DRAM system as a solution to the core-to-DRAM bandwidth bottleneck. By attacking energy consumption at the DRAM channel, chip, and bank level with integrated photoncis, we cut the power consumption of the DRAM system by 10x while remaining area neutral when compared to a projected electrical baseline.
by Chen Sun.
S.M.
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Chen, Raymond M. Eng Massachusetts Institute of Technology. "Photoacoustic photonic crystal fiber gas sensor." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41258.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 89-93).
Photoacoustic spectroscopy (PAS) is a form of laser spectroscopy that has demonstrated very high sensitivity for gas detection. Typically, PAS involves the absorption of a modulated laser beam by the gas species of interest, and the subsequent generation of acoustic waves at the modulation frequency. The amplitude of the acoustic signal, which can be measured by a microphone, can be amplified by several orders of magnitude with a properly designed gas cell used as an acoustic resonator. In recent times, hollow-core photonic crystal fiber (HC-PCF) has emerged as superior gas cell for standard absorption-based laser spectroscopy due to its small size, compatibility with fiber-based optical components, and easily attainable long light-gas interaction path lengths. However, the possibility of utilizing HC-PCF as a gas cell for PAS has yet to be explored. The size and structure of HC-PCF demands that a new method of PA signal detection must be proposed, because the conventional use of microphones for PAS is not applicable. This thesis describes the development of a proposed novel use of HC-PCF as a PA gas cell from theoretical support to experimental realization. A number of unresolved experimental issues prevented data on the performance of the constructed system from being obtained. These problems are discussed, and recommendations for further study, including several proposed measures to overcome these experimental issues, are made in the conclusion to the thesis.
by Raymond Chen.
M.Eng.
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Khilo, Anatol (Anatol M. ). "Integrated photonic analog-to-digital converters." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68490.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 161-172).
Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical imaging, and communication systems. Aperture jitter has been a major bottleneck on the way towards higher speeds and better accuracy. Photonic ADCs, which perform sampling using ultra-stable optical pulse trains generated by mode-locked lasers, have been investigated as a promising approach to overcome the jitter problem and bring ADC performance to new levels. This work demonstrates that the photonic approach can deliver on its promise by digitizing a 41 GHz signal with 7.0 effective bits and 52 dBc spur-free dynamic range (SFDR) using a discrete-component photonic ADC. This corresponds to 15 fs jitter, a 4-5 times improvement over the jitter of the best electronic ADCs, and an order of magnitude improvement over the jitter of electronic ADCs operating above 10 GHz. The feasibility of a practical photonic ADC is demonstrated by creating an integrated ADC with a modulator, filters, and photodetectors fabricated on a single silicon chip and using it to sample a 10 GHz signal with 3.5 effective bits and 39 dBc SFDR. In both experiments, a sample rate of 2.1 GSa/s was obtained by interleaving two 1.05 GSa/s channels; higher sample rates can be achieved by increasing the channel count. A key component of a multi-channel ADC - a dual multi-channel high-performance filter bank - is successfully implemented. A concept for broadband linearization of the silicon modulator, which is another critical component of the photonic ADC, is proposed. Nonlinear phenomena in silicon microring filters and their impact on ADC performance are analyzed, and methods to reduce this impact are proposed. The results presented in the thesis suggest that a practical integrated photonic ADC, which successfully overcomes the electronic jitter bottleneck, is possible today.
by Anatol Khilo.
Ph.D.
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Kononov, Ekaterina (Ekaterina R. ). "Modeling photonic links in Verilog-A." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/85432.
Full textAbstract:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-60).
Integrated photonic links are a promising emerging technology that can relieve the interconnect bottleneck in core-to-core and core-to-memory communications of modern processors. Developing and optimizing photonic link systems requires simulation of integrated photonic devices side-by-side with electronic devices at the device, circuit, and system level. In previous efforts to simulate photonic links, the optical and the electrical signals were treated in separate simulators, which resulted in some loss of accuracy. In this thesis, a library of photonic device models is developed in Verilog-A for use in seamless simulation of opto-electronic circuits in Cadence.
by Ekaterina Kononov.
M. Eng.
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Mower, Jacob. "Photonic quantum computers and communication systems." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/103851.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 123-137).
Quantum information processors have been proposed to solve classically intractable or unsolvable problems in computing, sensing, and secure communication. There has been growing interest in photonic implementations of quantum processors as they offer relatively long coherence lengths, precise state manipulation, and efficient measurement. In this thesis, we first present experimental techniques to generate on-chip, photonic quantum processors and then discuss protocols for fast and secure quantum communication. In particular, we describe how -to combine the outputs of multiple stochastic single-photon sources using a photonic integrated circuit to generate an efficient source of single photons. We then show designs for silicon-based quantum photonic processors that can be programmed to implement a large class of existing quantum algorithms and can lead to quicker testing of new algorithms than was previously possible. We will then present the integration of large numbers of high-efficiency, low-timing jitter single-photon detectors onto a silicon photonic integrated circuit. To conclude, we will present a quantum key distribution protocol that uses the robust temporal degree of freedom of entangled photons to enable fast, secure key exchange, as well as experimental results for implementing key distribution protocols using silicon photonic integrated circuits.
by Jacob Mower.
Ph. D.
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Yeng, Yi Xiang. "Photonic crystals for high temperature applications." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92969.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 95-104).
This thesis focuses on the design, optimization, fabrication, and experimental realization of metallic photonic crystals (MPhCs) for high temperature applications, for instance thermophotovoltaic (TPV) energy conversion and selective solar absorption. We begin with the exploration of refractory two-dimensional (2D) MPhC slabs as selective thermal emitters that approach the emittance of a blackbody below a cutoff wavelength, and zero emittance above the cutoff. The theory behind the enhancement of thermal emission is explored, leading to design handles that enable optimization for different applications. The fabrication process and extensive characterization of optimized 2D MPhCs are also presented. Next, we utilize non-linear global optimization tools to further optimize the 2D MPhCs for various TPV energy conversion systems. Performance estimates of realistic TPV systems incorporating experimentally demonstrated spectral control components are also presented. The numerical model is also used to pinpoint deficiencies in current TPV systems to uncover areas of future research to further improve system efficiencies. In particular, we show that air-filled 2D MPhCs suffer from decreased selective emission at larger polar angles, which can be circumvented by filling and coating the 2D MPhCs with a suitable refractory dielectric material. Finally, we explore PhC enhanced silicon (Si) photovoltaic cell based TPV systems numerically. Experiments towards record breaking efficiencies for Si cell based TPV systems are also presented and shown to agree well with numerical estimates, thus paving the way towards widespread adoption of what may be a promising highly efficient, portable, and reliable energy conversion system.
by Yi Xiang Yeng.
Ph. D.
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Lee, Jonathan Chaosung. "Fabrication and Characterization of Single-Crystal Diamond Photonic Cavities." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10964.
Full textAbstract:
Cavity quantum electrodynamics provide a platform to form a quantum network which connects individual quantum bits (qubits) via photon. Optical cavity, a device which traps photons in a confined volume can enhance the interaction between photons and the qubits serves as fundamental building block for a quantum network. Nitrogen vacancy (NV) centers in diamond has emerged as one of the leading solid-state qubits because of its long spin coherence time and single photon emission properties at room temperature. Diamond optical micro-cavities are highly sought after for coupling with NV centers. Fabrication of optical cavities from nano-crystalline diamond film has been demonstrated previously. The quality factor (Q) of such devices was limited by the material properties of the nano-crystalline diamond film. Fabrication of single-crystal diamond photonic cavities is challenging because there is no trivial way to form thin diamond film with optical isolation. In this thesis, we describe an approach to fabricate high quality single-crystal diamond optical cavities for coupling to NV centers in diamond. ingle-crystal diamond membranes were generated using an ion-slicing method. Whispering gallery modes were observed for the first time from microdisk cavities made from such material. However, the cavity Q (∼ 500) was limited by the ion damage created during processing. By using an homo-epitaxial overgrowth method, a high quality diamond film can be grown on the ion damaged membranes. Microdisk cavities with Q ∼ 3,000 were fabricated on these improved materials. Diamond membranes with a delta-doped layer of NV can be made using a slow overgrowth process which demonstrate the position and density of NV centers can be controlled in these membranes. Photonic crystal cavities with Q ∼ 4,000 were fabricated from the delta-doped membranes with cavity resonance near the zero phonon line of NV centers. Different color centers can also be introduced during the overgrowth process, and optical coupling of an ensemble of silicon vacancy centers is demonstrated by coupling to a diamond microdisk cavity. We believe the techniques developed in this thesis could contribute to building of a quantum photonic network using diamond as a platform.Engineering and Applied Sciences
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Mbomson, Ifeoma Grace. "Mid-infrared photonic sensors based on metamaterial structures." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7462/.
Full textAbstract:
In this work three different metallic metamaterials (MMs) structures such as asymmetric split ring resonators (A-SRRs), dipole and split H-shaped (ASHs) structures that support plasmonic resonances have been developed. The aim of the work involves the optimization of photonic sensor based on plasmonic resonances and surface enhanced infrared absorption (SEIRA) from the MM structures. The MMs structures were designed to tune their plasmonic resonance peaks in the mid-infrared region. The plasmonic resonance peaks produced are highly dependent on the structural dimension and polarisation of the electromagnetic (EM) source. The ASH structure particularly has the ability to produce the plasmonic resonance peak with dual polarisation of the EM source. The double resonance peaks produced due to the asymmetric nature of the structures were optimized by varying the fundamental parameters of the design. These peaks occur due to hybridization of the individual elements of the MMs structure. The presence of a dip known as a trapped mode in between the double plasmonic peaks helps to narrow the resonances. A periodicity greater than twice the length and diameter of the metallic structure was applied to produce narrow resonances for the designed MMs. A nanoscale gap in each structure that broadens the trapped mode to narrow the plasmonic resonances was also used. A thickness of 100 nm gold was used to experimentally produce a high quality factor of 18 in the mid-infrared region. The optimised plasmonic resonance peaks was used for detection of an analyte, 17β-estradiol. 17β-estradiol is mostly responsible for the development of human sex organs and can be found naturally in the environment through human excreta. SEIRA was the method applied to the analysis of the analyte. The work is important in the monitoring of human biology and in water treatment. Applying this method to the developed nano-engineered structures, enhancement factors of 10^5 and a sensitivity of 2791 nm/RIU was obtained. With this high sensitivity a figure of merit (FOM) of 9 was also achieved from the sensors. The experiments were verified using numerical simulations where the vibrational resonances of the C-H stretch from 17β-estradiol were modelled. Lastly, A-SRRs and ASH on waveguides were also designed and evaluated. These patterns are to be use as basis for future work.
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Noh, Jong Wook. "In-Plane, All-Photonic Transduction Method for Silicon Photonic Microcantilever Array Sensors." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/1965.
Full textAbstract:
We have invented an in-plane all-photonic transduction method for photonic microcantilever arrays that is scalable to large arrays for sensing applications in both bio- and nanotechnology. Our photonic transduction method utilizes a microcantilever forming a single mode rib waveguide and a differential splitter consisting of an asymmetric multimode waveguide and a Y-branch waveguide splitter. The differential splitter's outputs are used to form a differential signal that has a monotonic response to microcantilever deflection. A differential splitter using an amorphous silicon strip-loaded multimode rib waveguide is designed and fabricated to demonstrate the feasibility of the in-plane photonic transduction method. Our initial implementation shows that the sensitivity of the device is 0.135×10^-3 nm^-1 which is comparable to that of other readout methods currently employed for static-deflection based sensors. Through further analysis of the optical characteristics of the differential splitter, a new asymmetric double-step multimode rib waveguide has been devised for the differential splitter. The new differential splitter not only improves sensitivity and reduces size, but also eliminates several fabrication issues. Furthermore, photonic microcantilever arrays are integrated with the differential splitters and a waveguide splitter network in order to demonstrate scalability. We have achieved a measured sensitivity of 0.32×10^-3 nm^-1, which is 2.4 times greater than our initial result while the waveguide length is 6 times shorter. Analytical examination of the relationship between sensitivity and structure of the asymmetric double-step rib waveguide shows a way to further improve performance of the photonic microcantilever sensor. We have demonstrated experimentally that greater sensitivity is achieved when increasing the step height of the double-step rib waveguide. Moreover, the improved sensitivity of the photonic microcantilever system, 0.77×10^-3 nm^-1, is close to the best reported sensitivities of other transduction methods (~10^-3 nm^-1).
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Andersson, Olle. "Characterization of an On-chip Photonic Waveguide gas Sensor." Thesis, KTH, Skolan för teknik och hälsa (STH), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214719.
Full textAbstract:
Gas sensing in medical applications requiresmall, precise and sensitive sensors. This projecthas developed a laboratory setup for characterisationof a waveguide-based gas sensor for carbon dioxide andmethane working in the mid-IR range of 2 - 10 μm. Thissetup utilizes an IR-camera to image the waveguideswhen a mid-IR laser is coupled into them. Along thelaboratory work, a program for optimisation of waveguidelength has been made and a study of on-marketmedical carbon dioxide sensors has been done. Thelaboratory setup shows potential for good measurementof waveguide losses, but several problems was identifiedwith the measurement methods currently used. Fromthe sensor study, the standard performance for currentsensors is presented as well as areas where gas sensorscould be improved. Size, speed and accuracy were someof the characteristics a waveguide-based sensor couldimprove on and open up for new sensor application in,for example, hand-held medical devices.
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Saberi, Nahid. "Bandwith allocation and scheduling in photonic networks." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103004.
Full textAbstract:
This thesis describes a framework for bandwidth allocation and scheduling in the Agile All-Photonic Network (AAPN). This framework is also applicable to any single-hop communication network with significant signalling delay (such as satellite-TDMA systems). Slot-by-slot scheduling approaches do not provide adequate performance for wide-area networks, so we focus on frame-based scheduling. We propose three novel fixed-length frame scheduling algorithms (Minimum Cost Search, Fair Matching and Minimum Rejection) and a feedback control system for stabilization.MCS is a greedy algorithm, which allocates time-slots sequentially using a cost function. This function is defined such that the time-slots with higher blocking probability are assigned first. MCS does not guarantee 100% throughput, thought it has a low blocking percentage. Our optimum scheduling approach is based on modifying the demand matrix such that the network resources are fully utilized, while the requests are optimally served. The Fair Matching Algorithm (FMA) uses the weighted max-min fairness criterion to achieve a fair share of resources amongst the connections in the network. When rejection is inevitable, FMA selects rejections such that the maximum percentage rejection experienced in the network is minimized. In another approach we formulate the rejection task as an optimization problem and propose the Minimum Rejection Algorithm (MRA), which minimizes total rejection. The minimum rejection problem is a special case of maximum flow problem. Due to the complexity of the algorithms that solve the max-flow problem we propose a heuristic algorithm with lower complexity.
Scheduling in wide-area networks must be based on predictions of traffic demand and the resultant errors can lead to instability and unfairness. We design a feedback control system based on Smith's principle, which removes the destabilizing delays from the feedback loop by using a "loop cancelation" technique. The feedback control system we propose reduces the effect of prediction errors, increasing the speed of the response to sudden changes in traffic arrival rates and improving the fairness in the network through equalization of queue-lengths.
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Williams, Ryan Daniel. "Photonic integrated circuits for optical logic applications." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42025.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
The optical logic unit cell is the photonic analog to transistor-transistor logic in electronic devices. Active devices such as InP-based semiconductor optical amplifiers (SOA) emitting at 1550 nm are vertically integrated with passive waveguides using the asymmetric twin waveguide technique and the SOAs are placed in a Mach-Zehnder interferometer (MZI) configuration. By sending in high-intensity pulses, the gain characteristics, phase-shifting, and refractive indices of the SOA can be altered, creating constructive or deconstructive interference at the MZI output. Boolean logic and wavelength conversion can be achieved using this technique, building blocks for optical switching and signal regeneration. The fabrication of these devices is complex and the fabrication of two generations of devices is described in this thesis, including optimization of the mask design, photolithography, etching, and backside processing techniques. Testing and characterization of the active and passive components is also reported, confirming gain and emission at 1550 nm for the SOAs, as well as verifying evanescent coupling between the active and passive waveguides. In addition to the vertical integration of photonic waveguides, Esaki tunnel junctions are investigated for vertical electronic integration. Quantum dot formation and growth via molecular beam epitaxy is investigated for emission at the technologically important wavelength of 1310 nm. The effect of indium incorporation on tunnel junctions is investigated. The tunnel junctions are used to epitaxially link multiple quantum dot active regions in series and lasers are designed, fabricated, and tested.
by Ryan Daniel Williams.
Ph.D.