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1
Shankar, Raji. "Mid-Infrared Photonics in Silicon." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10988.
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The mid-infrared wavelength region (2-20 µm) is of great utility for a number of applications, including chemical bond spectroscopy, trace gas sensing, and medical diagnostics. Despite this wealth of applications, the on-chip mid-IR photonics platform needed to access them is relatively undeveloped. Silicon is an attractive material of choice for the mid-IR, as it exhibits low loss through much of the mid-IR. Using silicon allows us to take advantage of well-developed fabrication techniques and CMOS compatibility, making the realization of on-chip integrated mid-IR devices more realistic. The mid-IR wavelengths also afford the opportunity to exploit Si's high third-order optical nonlinearity for nonlinear frequency generation applications. In this work, we present a Si-based platform for mid-IR photonics, with a special focus on micro-resonators for strong on-chip light confinement in the 4-5 μm range. Additionally, we develop experimental optical characterization techniques to overcome the inherent difficulties of working in this wavelength regime. First, we demonstrate the design, fabrication, and characterization of photonic crystal cavities in a silicon membrane platform, operational at 4.4 μm (Chapter 2). By transferring the technique known as resonant scattering to the mid-IR, we measure quality (Q) factors of up to 13,600 in these photonic crystal cavities. We also develop a technique known as scanning resonant scattering microscopy to image our cavity modes and optimize alignment to our devices. Next, we demonstrate the electro-optic tuning of these mid-IR Si photonic crystal cavities using gated graphene (Chapter 3). We demonstrate a tuning of about 4 nm, and demonstrate the principle of on-chip mid-IR modulation using these devices. We then investigate the phenomenon of optical bistability seen in our photonic crystal cavities (Chapter 4). We discover that our bistability is thermal in origin and use post-processing techniques to mitigate bistability and increase Q-factors. We then demonstrate the design, fabrication, and characterization grating-coupled ring resonators in a silicon-on-sapphire (SOS) platform at 4.4 μm, achieving intrinsic Q-factors as high as 278,000 in these devices (Chapter 5). Finally, we provide a quantitative analysis of the potential of our SOS devices for nonlinear frequency generation and describe ongoing experiments in this regard (Chapter 6).Engineering and Applied Sciences
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Liu, Bo. "Integrated Microwave Photonics Signal Processing." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21633.
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The microwave photonics (MWP) is a promising technology in recent years in terms of processing high frequency microwave signals. It offers some advantages over electronic signal processing. Some of its advantages are high speed, low loss, wide range, light weight and immunity from electromagnetic interference. Because of these advantages, integrated MWP circuits can be used in many applications such as filters, phase shifters and time delay devices. Moreover, with the development of complementary metal-oxide semiconductor technology, MWP circuits can be integrated on a compact silicon-on-insulator platform. In this thesis, a new tunable single passband MWP filter based on on-chip silicon photonics technology and integrated MWP technology is designed. The new method has a great improvement in the selectivity of the filter by employing a dual-parallel Mach–Zehnder modulator (DPMZM). It simultaneously achieves the generation of phase-modulated signal and compensation for the undesired phase. The results show that the designed single passband MWP filter based on a DPMZM and an SOI single ring resonator, has a narrowband radio frequency response, where an average 10-dB bandwidth of 5.12 GHz is achieved. Another challenge for photonic circuit integration is coupling lights from optical fibers into photonic chips because of the spot size difference between fiber optical mode and waveguide mode. In this thesis, a simple solution is designed to achieve a horizontal integration of a fiber-chip spot size converting edge coupler, which only requires an inverse taper and a linear mode expander to couple light from a fiber and laterally expand the mode. Optimizing inverse taper parameters yields a 90% coupling efficiency from fiber to coupler output end for both the transvers electric and the transverse magnetic polarizations, which can be used for horizontal integration with a 50:50 polarization splitter.
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Herrera, Oscar Dario. "Nonlinear Photonics in Waveguides for Telecommunications." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338755.
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Bandwidth demands in global telecommunication infrastructures continue to rise and new optical techniques are needed to deal with massive data flows. Generating high bandwidth signals (> 40 GHz) using conventional modulation techniques is hindered by material limitations and fabrication complexities. Similarly, controlling such high bandwidths in both the temporal and spectral domain becomes more problematic using conventional electronic processes. Advances in electro-optic organic materials,
fibers/micro-fluidics integration, and nonlinear optics have significant potential for higher bandwidth modulation and temporal/spectral control. The work presented in this dissertation demonstrates the use of various nonlinear optical effects in new photonic device and system designs towards the generation and manipulation of highspeed optical pulses. First, an all fiber-based system utilizing an integrated carbon disulfide-filled liquidcore optical fiber (i-LCOF) and co-propagating pulses of comparable temporal lengths is presented. The slow light effect was observed in 1-meter of i-LCOF, where 18 ps pulses were delayed up to 34 ps through the use of stimulated Raman scattering. Delays greater than a pulse width indicate a potential application as an ultrafast controllable delay line for time division multiplexing in multi-Gb/s telecommunication systems. Similarly, an optically tunable frequency shift was observed using this system. Pulses experienced a full spectral bandwidth shift at low peak pump powers when utilizing the Raman-induced frequency shift and slow light effects. Numerical simulations of the pulse-propagation equations agree well with the observed shifts. Included in our simulations are the contributions of both the Raman cross-frequency shift and slow light effects to the overall frequency shift. These results make the system suitable for numerous applications including low power wavelength converters. Second, a silica/electro-optic (EO) polymer phase modulator with an embedded bowtie antenna is proposed for use as a microwave radiation receiver. The detection of high-frequency electromagnetic fields has been heavily studied for wireless data transfer. Recently there has been growing interest in the field of microwave photonics. We present the design and optimization of a waveguide with an EO polymer core and silica/sol-gel cladding. The effect of electrodes on the insertion losses and poling efficiency are also analyzed, and conditions for low-loss and high poling efficiency are established. Experimental results for a fabricated device with microwave-response between 10 - 14 GHz are presented. Finally, we present the design for a fast optical switch incorporating silicon as the passive waveguide structure and EO polymer as the active material. The design uses a simple directional coupler with coplanar electrodes and promises to have low cross-talk and high switching speed (on the order of nanoseconds). An initial design for a 1x2 switch is fabricated and tested, and future optimization processes are also presented.
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Zheng, Xin. "Graded photonic crystal for silicon photonics." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST063.
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Les cristaux photoniques à gradient (CPG) permettent une ingénierie de leur indice effectif, ce qui offre de nouveaux degrés de liberté pour la conception de dispositifs photoniques. Ils s’appréhendent par l’optique à gradient d’indice (GRIN optics), qui décrit des milieux inhomogènes dans lesquels la lumière ne se propage pas rectilignement. Il est ainsi possible d’envisager tout profil d’indice. Les CPG sont donc particulièrement attractifs pour la miniaturisation des composants optiques, notamment en photonique sur Silicium. Ils sont fondés sur la variation d’un paramètre de la maille élémentaire du cristal photonique (CP); ici, c’est le facteur de remplissage qui varie afin que l’indice effectif du CPG réalise le profil d’indice souhaité. Le but de cette thèse est d’explorer le potentiel des CPG en concevant des dispositifs à gradient d’indice sur la "plateforme" Silicium sur isolant (SOI) aux longueurs d’onde pour les télécommunications. C’est la chaine complète qui va de la conception à la caractérisation du dispositif, en passant par la simulation et la fabrication, qui est mise en œuvre. Nous nous sommes principalement concentrés sur deux instruments typiques de l’optique à gradient d’indice : la lentille de Mikaelian et le Half Maxwell Fish Eye (HMFE). Dans cette thèse, nous proposons une nouvelle méthode d’approximation de l’indice effectif adaptée à la "plateforme" SOI, que nous avons validée en concevant une lentille de Mikaelian (à profil d’indice sécante hyperbolique). Pour de tels dispositifs, il faut en effet tenir compte de deux indices effectifs : celui du mode guidé dans la couche de Silicium et celui du CP. Dans cette méthode, l’indice effectif du CP est d’abord calculé pour remplacer l’indice de la couche du mode guidé ; puis l’indice effectif de cette couche est calculé. Les résultats de simulation obtenus au moyen d’un logiciel commercial (méthode FDTD) montrent que la lentille ainsi conçue satisfait les prévisions analytiques, contrairement à ce que donnent les méthodes couramment utilisées. Nous l’avons alors appliquée au HMFE. Les dispositifs ont ensuite été fabriqués en salle blanche par lithographie par faisceau d’électrons (EBL) et par gravure plasma (ICP). Les différents CPG fabriqués consistent en des trous d’air répartis périodiquement dans la couche de Silicium, dont le diamètre minimal est d’environ 40 nm. Puis, ils ont été caractérisés en deux temps, notamment par microscopie en champ proche (SNOM). L’épaisseur de ces dispositifs est de quelques longueurs d’onde (3 ou 5 λ_0 environ), tandis la largeur de leur tâche focale est proche de la limite de diffraction (0.5 λ_0 environ). Ils fonctionnent sur une plage de longueurs d’onde de 150 nm environ. Les résultats de la lentille de Mikaelian ont été utilisés pour développer un convertisseur de taille de mode (taper) effectif sur quelques longueurs d’onde. Il est dix fois plus court qu’un convertisseur classique. Dans cette thèse, nous montrons aussi comment il est possible d’interpréter la propagation de l’onde EM dans ces composants à gradient d’indice sur "plateforme" SOI au moyen du principe de l’interféromètre multimode. En se propageant, les différents modes accumulent une différence de phase, qui se traduit par un battement qui modifie la distribution du champ EM, conduisant à la focalisation. La longueur caractéristique de ce battement est égale à la distance focale. Tous ces dispositifs sont étudiés pour s’intégrer dans des circuits de photonique intégréeGradient photonic crystals (GPhCs) enable the engineering of their effective index, opening up new degrees of freedom in photonic device design. They can be understood through gradient index optics (GRIN optics), which describe inhomogeneous media in which light does not propagate along straight paths. This makes it possible to consider any index profile. This makes GPhCs particularly attractive for the miniaturization of optical components, especially in silicon photonics. They are based on the variation of a parameter of the photonic crystal elemental cell (PhC); here, the filling factor is varied so that the effective index of the GPhC achieves the desired index profile. The aim of this thesis is to explore the potential of GPhCs by designing graded-index devices on the Silicon-On-Insulator (SOI) "platform" at telecom wavelengths. The complete chain from design to device characterization, including simulation and manufacturing, is implemented. We focused on two typical gradient index optics instruments: the Mikaelian lens and the Half Maxwell Fish Eye (HMFE). In this thesis, we propose a new effective index approximation method for the SOI "platform", which we have validated by designing a Mikaelian lens (with a hyperbolic secant index profile). For such devices, two effective indices need to be taken into account: that of the guided mode in the Silicon layer and that of the PhC. In this method, the effective index of the PhC is first calculated to replace the index of the guided mode layer; then the effective index of this layer is calculated. Simulation results obtained using commercial software (FDTD method) show that the lens designed in this way satisfies the analytical predictions, contrary to the results obtained with commonly used methods. We then applied it to HMFE.The devices were then fabricated in the cleanroom by electron beam lithography (EBL) and plasma etching (ICP). The individual GPhCs consisted of periodically distributed air holes in the Silicon layer, with a minimum diameter of around 40 nm. They were then characterized in two stages, notably by near-field microscopy (SNOM). These devices are only a few wavelengths thick (approx. 3 or 5 λ_0), while their focal spot width is close to the diffraction limit (approx. 0.5 λ_0). They operate over a wavelength range of around 150 nm. The Mikaelian lens results have been used to develop a mode size converter (taper), which is effective over a few wavelengths. It is ten times shorter than a conventional converter. In this thesis, we also show how it is possible to interpret EM wave propagation in these graded-index components on the SOI platforms using the multimode interferometer principle. As they propagate, the different modes accumulate a phase difference, resulting in a mode beat that modifies the EM field distribution, leading to focusing. The characteristic length of this mode beat is equal to the focal length. All these devices are studied for integration into integrated photonics circuits
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Seigneur, Hubert P. "Modeling and design of a photonic crystal chip hosting a quantum network made of single spins in quantum dots that interact via single photons." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4614.
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In this dissertation, the prospect of a quantum technology based on a photonic crystal chip hosting a quantum network made of quantum dot spins interacting via single photons is investigated. The mathematical procedure to deal with the Liouville-Von Neumann equation, which describes the time-evolution of the density matrix, was derived for an arbitrary system, giving general equations. Using this theoretical groundwork, a numerical model was then developed to study the spatiotemporal dynamics of entanglement between various qubits produced in a controlled way over the entire quantum network. As a result, an efficient quantum interface was engineered allowing for storage qubits and traveling qubits to exchange information coherently while demonstrating little error and loss in the process; such interface is indispensable for the realization of a functional quantum network. Furthermore, a carefully orchestrated dynamic control over the propagation of the flying qubit showed high-efficiency capability for on-chip single-photon transfer. Using the optimized dispersion properties obtained quantum mechanically as design parameters, a possible physical structure for the photonic crystal chip was constructed using the Plane Wave Expansion and Finite-Difference Time-Domain numerical techniques, exhibiting almost identical transfer efficiencies in terms of normalized energy densities of the classical electromagnetic field. These promising results bring us one step closer to the physical realization of an integrated quantum technology combining both semiconductor quantum dots and sub-wavelength photonic structures.ID: 029049734; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 247-254).
Ph.D.
Doctorate
Optics and Photonics
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Yamashita, Tsuyoshi. "Unraveling photonic bands : characterization of self-collimation in two-dimensional photonic crystals." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-06072005-104606/.
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Thesis (Ph. D.)--School of Materials Science and Engineering, Georgia Institute of Technology, 2006.Summers, Christopher, Committee Chair ; Chang, Gee-Kung, Committee Member ; Carter, Brent, Committee Member ; Wang, Zhong Lin, Committee Member ; Meindl, James, Committee Member ; Li, Mo, Committee Member.
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Oser, Dorian. "Integrated silicon photonics for quantum optics." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS455.
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La photonique silicium est un domaine prolifique de l’optique intégrée. Elle permet de miniaturiser de nombreuses fonctionnalités optiques, l’émission laser (en considérant les stratégies d’intégration hybride), la modulation électro-optique, le routage, la détection, pour les télécoms, les LIDAR ou la spectroscopie, la métrologie, les capteurs et laboratoires sur puce, toute en produisant à grande échelle avec une grande précision et à bas coût (grâce au technologies CMOS de la microélectronique). L’optique quantique, quant à elle, souffre d’une grande sensibilité aux vibrations et à l’environnement. Les montages optiques nécessitent stabilité, alignement parfait et un grand nombre d’éléments optiques, ce qui limite son développement à grande échelle. Inversement, tous ces aspects sont naturels en photonique intégrée. Le développement de la photonique quantique est ainsi susceptible de permettre l’implémentation à large échelle de systèmes de clés de cryptage pour les télécoms et le calcul quantique. Les prérequis de la photonique quantique sont globalement plus sévères que ceux de la photonique classique. La génération d’états quantiques nécessite notamment un niveau de réjection de la pompe de plus de 100 dB ; le niveau de bruit photonique ambiant sur la puce est également un facteur à soigner particulièrement dans la mesure où les paires de photons générées par les processus quantiques sont par principe de très faible puissance. Dans ce contexte, cette thèse aborde le développement de composants et de circuits pour la photonique quantique silicium. Le but est de générer des états intriqués en énergie-temps et de pouvoir les manipuler sur une puce. Cela va de la conception à l’utilisation des paires de photons, en passant par la fabrication des circuits intégrés optiques. La qualification des propriétés quantiques est aussi explorée afin de cerner les limitations de la plateforme silicium pour le domaine applicatif visé. L’esprit de ce travail est également de proposer des solutions restantes compatibles avec les canaux de télécommunications standard (ITU), de n’utiliser que des composants fibrés standards pour les connexions à réaliser, tout en restant compatibles avec les techniques de fabrication industrielle des grandes fonderies microélectroniques afin de permettre une future production à grand échelle des circuits photoniques quantiquesSilicon photonics is a dynamic research field of integrated optics. It allows to miniaturize numerous optical functionalities such as lasers, electro-optical modulators, routers, detectors, for telecom wavelengths, LIDAR, sensor, metrology or even spectroscopy, all while been able to propose large scale production high precision technologies. On another side, quantum optics suffers from difficulties to scale optical systems, requires extreme stability, perfect alignment, and many bulky optical elements, while solving these issues follows a natural path in integrated photonics. Development of integrated quantum photonics can thus open the door to cheap, powerful, and scalable systems for quantum cryptography, telecoms, and computation. In a significant way, quantum requirements are not the ones of classical circuits with respect to photonic components and circuits. The generation of quantum states indeed requires more than 100dB of pump laser rejection, while being able to manage ultra-low useful optical signals and get rid of on-chip optical noise. In this context, this thesis is dedicated to the study, dimension, realization, and characterization of silicon photonic components and circuits for quantum optics on a chip. The target goal is to generate entangled states in energy-time and manipulate them on chip. The qualification of the quantum properties is also explored to better understand the limitations of the silicon platform in the followed objectives. Another choice of this work is to stay in telecoms wavelength and aligned with the standard channels (ITU grid), to only use off-the-shelf components, all while been CMOS compatible and compliant with standard fabrication process, this to allow the possibility to produce on large scale
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Gray, David. "Molecular organic photonics." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/5593/.
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The work presented in this thesis is derived from experimentation in the field of molecular organic photonics. This is done from the standpoint that devices cannot be understood without recourse to the molecular properties and vice versa. A background of nonlinear optics and a brief introduction to the origins of molecular organic nonlinearity is given to aid understanding of the main points of the argument. The dipole moment of several organics was calculated using a simple capacitance method which has been successfully applied to reactive species. These dipole moment results were necessary in the extraction of βʷ from the µβʷ extracted from the EFISH technique. This experiment was performed at 1.064µm and 1.907µm with the latter wavelength being applied to the first in a new class of organic molecules. Results of the work on a number of techniques relevant to thin film devices are also presented. This culminated in an amplitude modulator case study that brought all the techniques together. Finally a discussion on the links between molecular and device related properties justifies the approach taken.
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Burr, Justin R. "Degenerate Band Edge Resonators in Silicon Photonics." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449233730.
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Chen, Li. "Hybrid Silicon and Lithium Niobate Integrated Photonics." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429660021.
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Sánchez, Diana Luis David. "High performance photonic devices for switching applications in silicon photonics." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/77150.
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El silicio es la plataforma más prometedora para la integración fotónica, asegurando la compatibilidad con los procesos de fabricación CMOS y la producción en masa de dispositivos a bajo coste. Durante las últimas décadas, la tecnología fotónica basada en la plataforma de silicio ha mostrado un gran crecimiento, desarrollando diferentes tipos de dispositivos ópticos de alto rendimiento.
Una de las posibilidades para continuar mejorando las prestaciones de los dispositivos fotónicos es mediante la combinación con otras tecnologías como la plasmónica o con nuevos materiales con propiedades excepcionales y compatibilidad CMOS. Las tecnologías híbridas pueden superar las limitaciones de la tecnología de silicio, dando lugar a nuevos dispositivos capaces de superar las prestaciones de sus homólogos electrónicos. La tecnología híbrida dióxido de vanadio/ silicio permite el desarrollo de dispositivos de altas prestaciones, con gran ancho de banda, mayor velocidad de operación y mayor eficiencia energética con dimensiones de la escala de la longitud de onda.
El objetivo principal de esta tesis ha sido la propuesta y desarrollo de dispositivos fotónicos de altas prestaciones para aplicaciones de conmutación. En este contexto, diferentes estructuras basadas en silicio, tecnología plasmónica y las propiedades sintonizables del dióxido de vanadio han sido investigadas para controlar la polarización de la luz y para desarrollar otras funcionalidades electro-ópticas como la modulación.Silicon is the most promising platform for photonic integration, ensuring CMOS fabrication compatibility and mass production of cost-effective devices. During the last decades, photonic technology based on the Silicon on Insulator (SOI) platform has shown a great evolution, developing different sorts of high performance optical devices. One way to continue improving the performance of photonic optical devices is the combination of the silicon platform with another technologies like plasmonics or CMOS compatible materials with unique properties. Hybrid technologies can overcome the current limits of the silicon technology and develop new devices exceeding the performance metrics of its counterparts electronic devices. The vanadium dioxide/silicon hybrid technology allows the development of new high-performance devices with broadband performance, faster operating speed and energy efficient optical response with wavelength-scale device dimensions. The main goal of this thesis has been the proposal and development of high performance photonic devices for switching applications. In this context, different structures, based on silicon, plasmonics and the tunable properties of vanadium dioxide, have been investigated to control the polarization of light and for enabling other electro-optical functionalities, like optical modulation.
El silici és la plataforma més prometedora per a la integració fotònica, assegurant la compatibilitat amb els processos de fabricació CMOS i la producció en massa de dispositius a baix cost. Durant les últimes dècades, la tecnologia fotònica basada en la plataforma de silici ha mostrat un gran creixement, desenvolupant diferents tipus de dispositius òptics d'alt rendiment. Una de les possibilitats per a continuar millorant el rendiment dels dispositius fotònics és per mitjà de la combinació amb altres tecnologies com la plasmònica o amb nous materials amb propietats excepcionals i compatibilitat CMOS. Les tecnologies híbrides poden superar les limitacions de la tecnologia de silici, donant lloc a nous dispositius capaços de superar el rendiment dels seus homòlegs electrònics. La tecnologia híbrida diòxid de vanadi/silici permet el desenvolupament de dispositius d'alt rendiment, amb gran ample de banda, major velocitat d'operació i major eficiència energètica en l'escala de la longitud d'ona. L'objectiu principal d'esta tesi ha sigut la proposta i desenvolupament de dispositius fotònics d'alt rendiment per a aplicacions de commutació. En este context, diferents estructures basades en silici, tecnologia plasmònica i les propietats sintonitzables del diòxid de vanadi han sigut investigades per a controlar la polarització de la llum i per a desenvolupar altres funcionalitats electró-òptiques com la modulació.
Sánchez Diana, LD. (2016). High performance photonic devices for switching applications in silicon photonics [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/77150
TESIS
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Baker, Christopher Charles. "Electroluminescent Thin Films for Integrated Optics Applications." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054903604.
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Ma, Jichi. "Nonlinear integrated photonics on silicon and gallium arsenide substrates." Doctoral diss., University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6314.
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Silicon photonics is nowadays a mature technology and is on the verge of becoming a blossoming industry. Silicon photonics has also been pursued as a platform for integrated nonlinear optics based on Raman and Kerr effects. In recent years, more futuristic directions have been pursued by various groups. For instance, the realm of silicon photonics has been expanded beyond the well-established near-infrared wavelengths and into the mid-infrared (3 – 5 ?m). In this wavelength range, the omnipresent hurdle of nonlinear silicon photonics in the telecommunication band, i.e., nonlinear losses due to two-photon absorption, is inherently nonexistent. With the lack of efficient light-emission capability and second-order optical nonlinearity in silicon, heterogeneous integration with other material systems has been another direction pursued. Finally, several approaches have been proposed and demonstrated to address the energy efficiency of silicon photonic devices in the near-infrared wavelength range.
In this dissertation, theoretical and experimental works are conducted to extend applications of integrated photonics into mid-infrared wavelengths based on silicon, demonstrate heterogeneous integration of tantalum pentoxide and lithium niobate photonics on silicon substrates, and study two-photon photovoltaic effect in gallium arsenide and plasmonic-enhanced structures.
Specifically, performance and noise properties of nonlinear silicon photonic devices, such as Raman lasers and optical parametric amplifiers, based on novel and reliable waveguide technologies are studied. Both near-infrared and mid-infrared nonlinear silicon devices have been studied for comparison. Novel tantalum-pentoxide- and lithium-niobate-on-silicon platforms are developed for compact microring resonators and Mach-Zehnder modulators. Third- and second-harmonic generations are theoretical studied based on these two platforms, respectively.
Also, the two-photon photovoltaic effect is studied in gallium arsenide waveguides for the first time. The effect, which was first demonstrated in silicon, is the nonlinear equivalent of the photovoltaic effect of solar cells and offers a viable solution for achieving energy-efficient photonic devices. The measured power efficiency achieved in gallium arsenide is higher than that in silicon and even higher efficiency is theoretically predicted with optimized designs. Finally, plasmonic-enhanced photovoltaic power converters, based on the two-photon photovoltaic effect in silicon using subwavelength apertures in metallic films, are proposed and theoretically studied.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics and Photonics
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Alam, Mohammad. "High performance magneto-optic garnet materials for integrated optics and photonics." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2012. https://ro.ecu.edu.au/theses/528.
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This work explores the preparation, characteristics and properties of highly bismuth (Bi) substituted, metal doped, iron garnet compounds and investigates their potential for various emerging applications in the visible and near infrared spectral regions.
Bi-substituted iron garnet and garnet-oxide nanocomposite films of generic composition type (Bi, Dy/Lu)3(Fe, Ga/Al)5O12 are prepared by using a radio frequency (RF) magnetron sputtering technique. The physical properties (crystallinity, film morphology, optical absorption spectra across the visible spectral range and the elemental composition of layers), and magneto-optic behaviour (Faraday rotation, hysteresis loops of Faraday rotation, and magnetic switching behaviour) of these sputtered garnet films are investigated in this work. These garnet materials possess high quality nanocrystalline thin-film microstructures and demonstrate excellent combination of optical and magneto-optical (MO) properties which makes them very attractive for use in magneto-optical applications. Record-high MO performance, in terms of the material’s MO figures of merit achieved (which exceeded most or all of the values reported previously for any semi-transparent MO materials across most of the visible spectrum), is achieved simultaneously with high Faraday rotation, making them suitable for a wide range of applications in integrated optics and photonics. The effects of annealing on the garnets of type (Bi,Dy)3(Fe,Ga)5O12, when performed in air atmosphere, are investigated and a systematic study is conducted to figure out the annealing behaviour and the crystallization kinetics of garnet formation within the garnet-bismuth oxide nanocomposites. Also, several nano-engineered magnetooptically active heterostructures (all-garnet multilayer-type thin film structures) based on magnetic layers with dissimilar uniaxial (Ku > 0) and in-plane (Ku < 0) magnetic anisotropies are prepared with the purpose of achieving the customised magnetic behaviour and properties (not attainable in single garnet layers) which are very attractive for the development of MO sensing devices and ultra-fast switches.
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Lyyttkäinen, Katja Johanna. "Control of complex structural geometry in optical fibre drawing /." Connect to full text, 2004. http://setis.library.usyd.edu.au/adt/public_html/adt-NU/public/adt-NU20041011.120247.
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Lyytikäinen, Katja Johanna. "Control of complex structural geometry in optical fibre drawing." Connect to full text, 2004. http://hdl.handle.net/2123/597.
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Thesis (Ph. D.)--University of Sydney, 2004.Title from title screen (viewed 14 May 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Includes bibliographical references. Also available in print form.
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Frantz, Jesse Arlo. "Selectively buried ion-exchanged waveguides for photonics applications." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/290069.
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Selectively buried ion-exchanged waveguides in glass are investigated theoretically and experimentally for use in low-loss coupling to other optical media. Selectively buried waveguides (SBWGs) are integrated optic structures in which light makes a transition from a buried waveguide with a maximum refractive index that lies 5-20 μm beneath the glass surface to a surface section with a maximum refractive index that lies at or near the surface. The buried sections provide low propagation losses and convenient coupling to optical fibers. Surface sections allow interaction between the guided mode and a superstrate material; in these sections the glass and superstrate form a composite waveguide in which the optical field propagates in both materials as a single optical mode. Adiabatic transition regions connect buried and surface sections. SBWGs are modelled by use of the finite difference method. The refractive index profile is first computed. The mode profiles and effective indices of the modes that the waveguide supports are then solved. The beam propagation method is applied to determine how the mode changes as it propagates through the SBWG. The transition from a buried to a surface waveguide is modelled, and it is found that the transition is adiabatic and low-loss. The surface section is modelled with a polymer superstrate, and the confinement factor in the polymer is computed. Ag⁺/K⁺ ion exchange is used to fabricate SBWGs, and a thorough experimental investigation of their properties is conducted. Refractive index profiles in buried, surface, and transition regions are measured by use of the refracted near-field method, and it is demonstrated that the maximum refractive index lies approximately 20 μm beneath the surface in buried regions and approximately 3 μm beneath the surface in surface regions. A novel method of simultaneously measuring the mode profile and depth of an ion-exchanged waveguide is presented and applied to SBWGs. Losses in these devices are measured, and the magnitudes of various losses are estimated.
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Douglass, Kyle. "Mesoscale Light-Matter Interactions." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5933.
Full textAbstract:
Mesoscale optical phenomena occur when light interacts with a number of different types of materials, such as biological and chemical systems and fabricated nanostructures. As a framework, mesoscale optics unifies the interpretations of the interaction of light with complex media when the outcome depends significantly upon the scale of the interaction. Most importantly, it guides the process of designing an optical sensing technique by focusing on the nature and amount of information that can be extracted from a measurement.
Different aspects of mesoscale optics are addressed in this dissertation which led to the solution of a number of problems in complex media. Dynamical and structural information from complex fluids—such as colloidal suspensions and biological fluids—was obtained by controlling the size of the interaction volume with low coherence interferometry. With this information, material properties such as particle sizes, optical transport coefficients, and viscoelastic characteristics of polymer solutions and blood were determined in natural, realistic conditions that are inaccessible to conventional techniques.
The same framework also enabled the development of new, scale-dependent models for several important physical and biological systems. These models were then used to explain the results of some unique measurements. For example, the transport of light in disordered photonic lattices was interpreted as a scale-dependent, diffusive process to explain the anomalous behavior of photon path length distributions through these complex structures. In addition, it was demonstrated how specialized optical measurements and models at the mesoscale enable solutions to fundamental problems in cell biology. Specifically, it was found for the first time that the nature of cell motility changes markedly with the curvature of the substrate that the cells
iv
move on. This particular work addresses increasingly important questions concerning the nature of cellular responses to external forces and the mechanical properties of their local environment.
Besides sensing of properties and modeling behaviors of complex systems, mesoscale optics encompasses the control of material systems as a result of the light-matter interaction. Specific modifications to a material's structure can occur due to not only an exchange of energy between radiation and a material, but also due to a transfer of momentum. Based on the mechanical action of multiply scattered light on colloidal particles, an optically-controlled active medium that did not require specially tailored particles was demonstrated for the first time. The coupling between the particles and the random electromagnetic field affords new possibilities for controlling mesoscale systems and observing nonequilibrium thermodynamic phenomena.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
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Borghi, Massimo. "Linear, nonlinear and quantum optics in Silicon Photonics." Doctoral thesis, Università degli studi di Trento, 2016. https://hdl.handle.net/11572/369126.
Full textAbstract:
This thesis work covers both classical and quantum aspects of nonlinear propagation of photons in nanophotonic Silicon waveguides. The work has been carried out within the framework of the project SIQURO, which aims to bring the quantum world into integrated photonics by using
the Silicon platform and, therefore, permitting in a natural way the integration of quantum photonics with electronics. The research towards on chip bright quantum sources of photon pairs has been done by investigating Multi Modal Four Wave Mixing in micrometer-size waveguides, thus exploiting the large third order nonlinearity of Silicon. The possibility to induce second order nonlinearities by straining its unit cell has been also analyzed through the study of the electro-optic effect. This has been done with the aim to promote Silicon as a platform for the integration of quantum sources of entangled photons based on
Spontaneous Parametric Down Conversion. New quantum interference effects have been reported in a free space
unbalanced Mach Zehnder interferometer asymmetrically excited by colour entangled photon pairs.
Innovative designs of integrated quantum circuits have been proposed, which extend the capabilities of the quantum
circuits demonstrated so far and provide additional functionalities. This work represents a step forward to the
realization of self subsistent integrated devices for quantum enhanced measurement, quantum computation and quantum crypthography.
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Borghi, Massimo. "Linear, nonlinear and quantum optics in Silicon Photonics." Doctoral thesis, University of Trento, 2016. http://eprints-phd.biblio.unitn.it/1693/1/PhDThesis_Borghi_Final.pdf.
Full textAbstract:
This thesis work covers both classical and quantum aspects of nonlinear propagation of photons in nanophotonic Silicon waveguides. The work has been carried out within the framework of the project SIQURO, which aims to bring the quantum world into integrated photonics by using
the Silicon platform and, therefore, permitting in a natural way the integration of quantum photonics with electronics. The research towards on chip bright quantum sources of photon pairs has been done by investigating Multi Modal Four Wave Mixing in micrometer-size waveguides, thus exploiting the large third order nonlinearity of Silicon. The possibility to induce second order nonlinearities by straining its unit cell has been also analyzed through the study of the electro-optic effect. This has been done with the aim to promote Silicon as a platform for the integration of quantum sources of entangled photons based on
Spontaneous Parametric Down Conversion. New quantum interference effects have been reported in a free space
unbalanced Mach Zehnder interferometer asymmetrically excited by colour entangled photon pairs.
Innovative designs of integrated quantum circuits have been proposed, which extend the capabilities of the quantum
circuits demonstrated so far and provide additional functionalities. This work represents a step forward to the
realization of self subsistent integrated devices for quantum enhanced measurement, quantum computation and quantum crypthography.
21
Deotare, Parag. "Nanobeam Cavities for Reconfigurable Photonics." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10414.
Full textAbstract:
We investigate the design, fabrication, and experimental characterization of high quality factor photonic crystal nanobeam cavities, with theoretical quality factors of \(1.4 × 10^7\) in silicon, operating at ~1550 nm. By detecting the cross-polarized resonantly scattered light from a normally incident laser beam, we measure a quality factor of nearly \(7.5 × 10^5\). We show on-chip integration of the cavities using waveguides and an inverse taper geometry based mode size converters, and also demonstrate tuning of the optical resonance using thermo-optic effect. We also study coupled cavities and show that the single nanobeam cavity modes are coupled into even and odd superposition modes. Using electrostatic force and taking advantage of the highly dispersive nature of the even mode to the nanobeam separation, we demonstrate dynamically reconfigurable optical filters tunable continuously and reversibly over a 9.5 nm wavelength range. The electrostatic force, obtained by applying bias voltages directly to the nanobeams, is used to control the spacing between the nanobeams, which in turn results in tuning of the cavity resonance. The observed tuning trends were confirmed through simulations that modeled the electrostatic actuation as well as the optical resonances in our reconfigurable geometries. Finally we demonstrate reconfiguration of coupled cavities by using optical gradient force induced mechanical actuation. Propagating waveguide modes that exist over wide wavelength range are used to actuate the structures and in that way control the resonance of a localized cavity mode. Using this all-optical approach, more than 18 linewidths of tuning range is demonstrated. Using an on-chip temperature self-referencing method that we developed, we determined that 20% of the total tuning was due to optomechanical reconfiguration and the rest due to thermo-optic effects. By operating the device at frequencies higher than the thermal cut-off, we show high speed operation dominated by just optomechanical effects. Independent control of mechanical and optical resonances of our structures, by means of optical stiffening, is also demonstrated.Engineering and Applied Sciences
22
Zeng, Xiaoge. "Integrated nonlinear photonics based on coupled-cavity resonator systems." Thesis, University of Colorado at Boulder, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10244962.
Full textAbstract:
Efficient nonlinear optical devices are designed and demonstrated in "photonic molecule''-like coupled-cavity resonator systems on a semiconductor chip. A coupled-cavity resonator may be designed to support distributed supermodes, and to allow independent control of the resonant frequency and linewidth of each supermode. Such control allows reduction of dispersion without compromising effective nonlinearity in the resonator, as well as the design of anisotropic output coupling or radiation that allows optimized nonlinear functions. Therefore this resonator manifests itself as a favorable platform for building nonlinear devices including optical parametric wavelength converters and oscillators based on four-wave mixing that call for different couplings to the signal, pump and idler modes. A physical model based on coupled-mode theory describes all relevant linear and nonlinear processes in triply-resonant microcavities, and a generalization of the usual nonlinear figure of merit is proposed to evaluate the effects of distributed supermodes on nonlinear conversion efficiency in such devices. Experimental work is presented that demonstrates coupled cavity devices for wavelength conversion in crystalline silicon, where two-photon absorption sets conversion efficiency limitations. In addition, an investigation of deposition conditions of hydrogenated amorphous silicon is described where amorphous silicon allows for a higher nonlinear figure of merit than crystalline silicon, promising increased performance in such devices. More generally, mode interference and coupling in coupled-cavity resonators, as a unique degree of freedom in integrated optics, is explored through designs of linear devices including efficient optical filters, wavelength converters, and modulators.
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Fitzgerald, Joseph P. S. "Aberration Corrected Photoemission Electron Microscopy with Photonics Applications." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2192.
Full textAbstract:
Photoemission electron microscopy (PEEM) uses photoelectrons excited from material surfaces by incident photons to probe the interaction of light with surfaces with nanometer-scale resolution. The point resolution of PEEM images is strongly limited by spherical and chromatic aberration. Image aberrations primarily originate from the acceleration of photoelectrons and imaging with the objective lens and vary strongly in magnitude with specimen emission characteristics. Spherical and chromatic aberration can be corrected with an electrostatic mirror, and here I develop a triode mirror with hyperbolic geometry that has two adjacent, field-adjustable regions. I present analytic and numerical models of the mirror and show that the optical properties agree to within a few percent. When this mirror is coupled with an electron lens, it can provide a large dynamic range of correction and the coefficients of spherical and chromatic aberration can be varied independently. I report on efforts to realize a triode mirror corrector, including design, characterization, and alignment in our microscope at Portland State University (PSU). PEEM may be used to investigate optically active nanostructures, and we show that photoelectron emission yields can be identified with diffraction, surface plasmons, and dielectric waveguiding. Furthermore, we find that photoelectron micrographs of nanostructured metal and dielectric structures correlate with electromagnetic field calculations. We conclude that photoemission is highly spatially sensitive to the electromagnetic field intensity, allowing the direct visualization of the interaction of light with material surfaces at nanometer scales and over a wide range of incident light frequencies.
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Gutiérrez, Campo Ana María. "Development of integrated silicon photonics modulation devices for digital and analog applications." Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/33330.
Full textAbstract:
Silicon photonics is one of the most exciting and fastest growing photonic technologies
in recent years. The salient feature of this technology is its compatibility with the
mature silicon IC manufacturing based on complementary metal-oxide semiconductor
(CMOS) processes widely used in microelectronic industry. Another motivation is the
availability of high-quality silicon-on-insulator (SOI) planar waveguide circuits that
offer strong optical confinement due to the high index contrast between silicon (n=3.45)
and SiO2 (n=1.45). This opens up miniaturization and very large scale integration of
photonic devices allowing photonic integrated circuits for a wide range of applications
and markets, from optical telecommunications to bio-photonic devices or precise fibre
sensors. Optical modulators are key building-blocks for high speed signal transmission
and information processing in any photonic interconnection solution. The work
developed in this thesis, as part of the objectives of the European project HELIOS in
which it is framed, is essentially focused on realizing compact and efficient modulators
integrated on silicon chips.
The thesis consists of three main chapters as well as the concluding section on the
work accomplished. Chapter one is aimed at giving a general description of the benefits
of using silicon photonics, showing its challenges and opportunities as well as at giving
a deeply overview of all issues related to the electro-optic modulation. Chapter two is
devoted to develop silicon modulators with high features for digital applications.
Specifically, new optical structures different to the conventional ones are presented with
the aim of enhancing the modulation performance or at least several critical parameters
in the modulation. Chapter three is dedicated to the analog applications. The concept of
microwave photonics is described as well as different researches carried out in the
analog scope for application in the field of integrated microwave photonics, all of them
using CMOS-compatible electro-optic silicon modulators which validate the potential of
silicon photonics as a promising approach for enabling the development of integrated
microwave photonics applications. Finally, conclusions on the work realized are
provided in Chapter 4.La fotónica de silicio es una de las tecnologías fotónicas que está experimentando un crecimiento más excitante y rápido en los últimos años. La característica más destacada de esta tecnología es su compatibilidad con las maduras técnicas de fabricación de circuitos integrados de silicio basadas en los procesos ¿complementary metal-oxide semiconductor¿ (CMOS) ampliamente utilizados en la industria microelectrónica. Otra motivación es la disponibilidad de circuitos de guía de ondas planas de silicio sobre aislante (SOI) de alta calidad que ofrecen un fuerte confinamiento óptico debido al alto contraste índices entre el silicio (n=3,45) y el SiO2 (n = 1,45). Esto abre las puertas a la miniaturización y a la integración a gran escala de dispositivos fotónicos lo que resulta en circuitos fotónicos integrados para una amplia gama de aplicaciones y mercados, desde telecomunicaciones ópticas a dispositivos bio-fotónicos o sensores de fibra precisos. Los moduladores ópticos son elementos básicos fundamentales para la transmisión de señales a alta velocidad y el procesado de información en cualquier solución de interconexión fotónica. El trabajo desarrollado en esta tesis, como parte del los objetivos del proyecto Europeo HELIOS en el que está enmarcada, se centra fundamentalmente en realizar moduladores compactos y eficientes, integrados en chips de silicio. La tesis consiste en 3 capítulos principales así como una sección de conclusiones del trabajo conseguido. El capítulo uno está destinado a dar una descripción general de los beneficios del uso de la fotónica de silicio, mostrando sus retos y oportunidades, así como a dar una visión profunda de todos los aspectos relacionados con la modulación electro-óptica. El capítulo dos está dedicado a desarrollar moduladores de silicio de altas prestaciones para aplicaciones digitales. Específicamente, se presentan nuevas estructuras ópticas diferentes a las convencionales con el objetivo de mejorar el rendimiento de la modulación o al menos algunos parámetros críticos en la modulación. El tercer capítulo se dedica a las aplicaciones analógicas. Se describe el concepto de la fotónica de microondas, así como diferentes investigaciones llevadas a cabo en el ámbito analógico para su aplicación en el campo de la fotónica integrada de microondas, todas ellas usando moduladores electro-ópticos de silicio compatibles con los procesos de fabricación CMOS, lo que valida el potencial de la fotónica de silicio como un prometedor enfoque para permitir el desarrollo de aplicaciones de la fotónica integrada de microondas. Por último, las conclusiones sobre el trabajo realizado se proporcionan en el Capítulo 4.
Gutiérrez Campo, AM. (2013). Development of integrated silicon photonics modulation devices for digital and analog applications [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/33330
TESIS
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Ventura, Michael James. "Fabrication and characterisation of three-dimensional passive and active photonic crystals." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/35914.
Full textAbstract:
Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, Centre for Micro-Photonics, 2008.Submitted for the degree of Doctor of Philosophy, Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, 2008. Typescript. Bibliography: p. 104-118.
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Choi, Jiyeon. "Femtosecond laser Written Volumetric Diffractive Optical Elements and Their Applications." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6230.
Full textAbstract:
Since the first demonstration of femtosecond laser written waveguides in 1996, femtosecond laser direct writing (FLDW) has been providing a versatile means to fabricate embedded 3-D microstructures in transparent materials. The key mechanisms are nonlinear absorption processes that occur when a laser beam is tightly focused into a material and the intensity of the focused beam reaches the range creating enough free electrons to induce structural modification. One of the most useful features that can be exploited in fabricating photonic structures is the refractive index change which results from the localized energy deposition. The laser processing system for FLDW can be realized as a compact, desktop station, implemented by a laser source, a 3-D stage and focusing optics. Thus, FLDW can be readily adopted for the fabrication of the photonic devices. For instance, it has been widely employed in various areas of photonic device fabrication such as active and passive waveguides, couplers, gratings, opto-fluidics and similar applications. This dissertation describes the use of FLDW towards the fabrication of custom designed diffractive optical elements (DOE's). These are important micro-optical elements that are building blocks in integrated optical devices including on-chip sensors and systems. The fabrication and characterization of laser direct written DOEs in different glass materials is investigated. The design and performance of a range of DOE's is described, especially, laser-written embedded Fresnel zone plates and linear gratings. Their diffractive efficiency as a function of the fabrication parameters is discussed and an optimized fabrication process is realized. The potential of the micro-DOEs and their integration shown in this dissertation will impact on the fabrication of future on-chip devices involving customized DOEs that will serve great flexibility and multi-functional capability on sensing, imaging and beam shaping.Ph.D.
Doctorate
Optics and Photonics
Optics
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Weed, Matthew. "Wavelength scale resonant structures for integrated photonic applications." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5888.
Full textAbstract:
An approach to integrated frequency-comb filtering is presented, building from a background in photonic crystal cavity design and fabrication. Previous work in the development of quantum information processing devices through integrated photonic crystals consists of photonic band gap engineering and methods of on-chip photon transfer. This work leads directly to research into coupled-resonator optical waveguides which stands as a basis for the primary line of investigation. These coupled cavity systems offer the designer slow light propagation which increases photon lifetime, reduces size limitations toward on-chip integration, and offers enhanced light-matter interaction. A unique resonant structure explained by various numerical models enables comb-like resonant clusters in systems that otherwise have no such regular resonant landscape (e.g. photonic crystal cavities). Through design, simulation, fabrication and test, the work presented here is a thorough validation for the future potential of coupled-resonator filters in frequency comb laser sources.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
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Ayre, Melanie. "Photonic crystal interfaces : a design-driven approach." Thesis, St Andrews, 2006. http://hdl.handle.net/10023/143.
Full text
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Zhu, Likai. "Computationally efficient digital backward propagation for fiber nonlinearity compensation." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4728.
Full textAbstract:
The next generation fiber transmission system is limited by fiber nonlinearity. A distributed nonlinearity compensation method, known as Digital Backward Propagation (DBP), is necessary for effective compensation of the joint effect of dispersion and nonlinearity. However, in order for DBP to be accurate, a large number of steps are usually required for long-haul transmission, resulting in a heavy computational load. In real time DBP implementation, the FIR filters can be used for dispersion compensation and account for most of the computation per step. A method of designing a complementary filter pair is proposed. The individual errors in the frequency response of the two filters in a complementary filter pair cancel each other. As a result, larger individual filter error can be tolerated and the required filter length is significantly reduced. Unequal step size can be used in DBP to minimize the number of steps. For unrepeatered transmission with distributed Raman amplification, the Raman gain as a function of the distance and the effective fiber length of each DBP step need to be calculated by solving the differential equations of Raman amplification. The split-step DBP is performed only for transmission where the signal power is high. In comparison with solving the nonlinear Schrodinger equation (NLSE) for the total field of the WDM signal, solving the coupled NLSE requires a smaller step number and a lower sampling rate. In addition, the phase-locking between the local oscillators is not necessary for solving the coupled NLSE. The XPM compensation of WDM long-haul transmission by solving the coupled NLSE is experimentally demonstrated. At the optimum power level of fiber transmission, the total nonlinear phase shift is on the order of 1 radian. Therefore, for transoceanic fiber transmission systems which consist of many (>100) amplified fiber spans, the nonlinear effects in each span are weak. As a result, the optical waveform evolution is dominated by the dispersion. Taking advantage of the periodic waveform evolution in periodically dispersion managed fiber link, the DBP of K fiber spans can be folded into one span with K times the nonlinearity. This method can be called "distance-folded DBP". Under the weakly nonlinear assumption, the optical waveform repeats at locations where accumulated dispersions are identical. Consequently, the nonlinear behavior of the optical signal also repeats at locations of identical accumulative dispersion. Hence for a fiber link with arbitrary dispersion map, the DBP steps can be folded according to the accumulated dispersion. Experimental results show considerable savings in computation using this "dispersion-folded DBP" method. Simulation results show that the dramatically reduced computational load makes the nonlinearity-compensated dispersion-managed fiber link a competitive candidate for the next-generation transmission systems.ID: 031001391; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Title from PDF title page (viewed May 28, 2013).; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references.
Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
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Atabaki, Amir Hossein. "Reconfigurable silicon photonic devices for optical signal processing." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41207.
Full textAbstract:
Processing of high-speed data using optical signals is a promising approach for tackling the bandwidth and speed challenges of today's electronics. Realization of complex optical signal processing functionalities seems more possible than any time before, thanks to the recent achievements in silicon photonics towards large-scale photonic integration. In this Ph.D. work, a novel thermal reconfiguration technology is proposed and experimentally demonstrated for silicon photonics that is compact, low-loss, low-power, fast, with a large tuning-range. These properties are all required for large-scale optical signal processing and had not been simultaneously achieved in a single device technology prior to this work. This device technology is applied to a new class of resonator-based devices for reconfigurable nonlinear optical signal processing. For the first time, we have demonstrated the possibility of resonance wavelength tuning of individual resonances and their coupling coefficients. Using this new device concept, we have demonstrated tunable wavelength-conversion through four-wave mixing in a resonator-based silicon device for the first time.
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Tsia, Kin Man. "Optical resonances in photonic-crystal-embedded microcavities /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202005%20TSIA.
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Zhang, Ziyang. "Silicon-based Photonic Devices : Design, Fabrication and Characterization." Doctoral thesis, Stockholm : Mikroelektronik och tillämpad fysik, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4647.
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Shen, Linping Huang Wei-Ping. "Modeling and design of photonic crystal waveguides and fibers /." *McMaster only, 2003.
Find full text
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Salandrino, Alessandro. "Electromagnetic propagation anomalies in waveguiding structures and scattering systems." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5024.
Full textAbstract:
The effects related to diffraction and interference are ubiquitous in phenomena involving electromagnetic wave propagation, and are accurately predicted and described within the framework of classical electrodynamics. In the vast majority of the cases the qualitative features of the evolution of a propagating wave can be inferred even without detailed calculations. A field distribution will spread upon propagation, will accumulate phase along the direction of power flow, will exert mechanical forces upon scattering objects in the direction of propagation etc. When such predictions fail, counterintuitive effects and new functionalities can be engineered. In this work a series of exceptional cases under different degrees of field confinement have been isolated. In such instances the electromagnetic behavior significantly deviates from conventional cases. In particular, considering structures with monodimensional field confinement, the only possible class of diffraction free surface waves has been introduced. Again within the context of surface waves the mechanism of Enhanced Evanescent Tunneling (EET) has been proposed, which allows a net power flow to be sustained by evanescent fields only with applications to sub-diffraction imaging. Increasing the degree of field confinement, a unique class of fully dielectric waveguide arrays able to support negative effective index modes has been theoretically demonstrated. Finally the opto-mechanical consequences of such effective negative index environments have been studied, highlighting counterintuitive properties. Instrumental to these findings was the introduction of a general theory of optical forces in terms of vector spherical harmonics.ID: 030423150; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 115-125).
Ph.D.
Doctorate
Optics and Photonics
35
Sun, Jie. "Fast-Response Liquid Crystals for Photonic and Display Applications." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6025.
Full textAbstract:
Liquid crystals (LCs) are attractive for many applications such as information displays, spatial light modulators, and adaptive optics because the optical properties of these devices are electrically tunable. For most display and photonic applications, response time is a critical parameter especially for spatial light modulators that requires at least 2? phase change. This problem gets more severe as the wavelength increases because a thicker LC layer is needed, which results in a slower response time. A typical E7 nematic liquid crystal cell with 2? phase change shows a response time longer than 100 ms at room temperature, which is too slow. Therefore, solutions for achieving fast response time are in high demand.
In this dissertation, several approaches for achieving submillisecond response time are investigated. In Chapter 2, we begin by introducing dual frequency liquid crystals (DFLCs) which provide possibility to achieve submillisecond rise time and decay time. We developed a DFLC mixture with a record-high birefringence (?n=0.39 at ?=633nm) based on phenyl-tolane compounds, which exhibit a positive dielectric anisotropy (??) and modest dielectric relaxation frequency.
In Chapter 3, a phase modulator with 4? phase change and 400 &"181;s average gray-to-gray response time is demonstrated using a sheared polymer network liquid crystal (SPNLC). This device exhibits a low scattering at ?=532 nm due to the employed material set and shearing technique. We also discuss the application of SPNLCs for 3D displays.
In Chapter 4, we studied the temperature effect on the splay elastic constant of polymer network liquid crystal (PNLC). Due to the existence of polymer network, the temperature dependent splay elastic constant of the LC cell deviates from the model for nematic LCs.
In Chapter 5, we focus on PNLC light modulators. This technology is attractive because it can achieve submillisecond response time while maintaining a large phase change. However, the light scattering loss caused by grain boundaries of liquid crystal multi-domains at voltage-on state hinders the widespread application of PNLCs. By optimizing liquid crystal host, polymer, and proper curing process, we successfully eliminate light scattering from short wave infrared region (1.55 ?m) to visible range.
In Chapter 6, we introduce a reconfigurable fabrication technique of tunable liquid crystal devices. Based on this technique and our scattering-free PNLCs, we developed a series of fast switching LC devices such as LC prism, grating and lens. The application of this technology in 3D lenticular lens development is also discussed. This technique provides a great flexibility for designing and fabricating LC photonic devices with desired refractive index profile.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
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Alam, Mohammad Zahirul. "Experiments in Nonlinear Optics with Epsilon-Near-Zero Materials." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41088.
Full textAbstract:
Nonlinear optics is the study of interactions of materials with intense light beams made possible by the invention of laser. Arguably the most trivial but technologically most important nonlinear optical effect is the intensity-dependent nonlinear refraction: an intense light beam can temporarily and reversibly change the refractive index of a material. However, the changes to the refractive index of a material due to the presence of a strong laser beam are very weak---maximum on the order of $10^{-3}$---and tend to be a small fraction of the linear refractive index. It must be noted that at optical frequencies vacuum has a refractive index of 1 and glass has a refractive index of 1.5. Thus, one of the foundational assumptions of nonlinear optics is that the nonlinear optical changes to material properties are always a small perturbation to the linear response. In the 58-year history of nonlinear optics, one of the overarching themes of research has been to find ways to increase the efficiency of nonlinear interactions.
This thesis is a collection of six manuscripts motivated by our experimental finding that at least in a certain class of materials the above long-standing view of nonlinear optics does not necessarily hold true. We have found that in a material with low refractive index, known as an epsilon-near-zero material or ENZ material, the nonlinear changes to the refractive index can be a few times larger than the linear refractive index, i.e. the nonlinear response becomes the dominant response of the material in the presence of an intense optical beam.
We believe that the results presented in this thesis collectively make a convincing case that ENZ materials are a promising platform for nonlinear nano-optics.
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Allen, Kenneth Wayne Jr. "Waveguide, photodetector, and imaging applications of microspherical photonics." Thesis, The University of North Carolina at Charlotte, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3685782.
Full textAbstract:
Dielectric microspheres with diameters (D) on the order of several wavelengths of light have attracted increasing attention from the photonics community due to their ability to produce extraordinarily tightly focused beams termed "photonic nanojets," to be used as microlenses for achieving optical super-resolution or to develop sensors based on whispering gallery mode resonances. In this dissertation, we study the optical properties of more complicated structures formed by multiple spheres which can be assembled as linear chains, clusters or arrays, integrated with waveguides or embedded inside other materials to achieve new optical properties or device functionalities.
For linear chains of polystyrene microspheres (n=1.59), we observed a transition from the regime of geometrical optics (at D>20 times the wavelength ) to the regime of wave optics (at D<20 times the wavelength ). We showed that this transition is accompanied by a dramatic change of focusing and optical transport properties of microsphere-chain waveguides. The results are found to be in qualitative agreement with numerical modeling.
We developed, designed, and tested a single-mode microprobe device based on spheres integrated with a waveguide for ultraprecise laser surgery. Our design is optimized using a hollow-core microstructured fiber as a delivery system with a single-mode Er:YAG laser operating at an illuminating wavelength of 2.94 micron. Using a high-index (n∼1.7-1.9) microsphere as the focusing element we demonstrate experimentally a beam waist of ∼4 times the wavelength, which is sufficiently small for achieving ultraprecise surgery.
For embedded microspherical arrays, we developed a technology to incorporate high-index (n∼1.9-2.1) spheres inside thin-films made from polydimethylsiloxane (PDMS). We showed that by using liquid lubrication, such thin-films can be translated along the surface to investigate structures and align different spheres with various objects. Rigorous resolution treatment was implemented and we demonstrated a resolution of ∼1/7 of the wavlength of illumination, which can be obtained by such thin-films.
We experimentally demonstrated that microspheres integrated with mid-IR photodetectors produce up to 100 times photocurrent enhancement over a broad range of wavelengths from 2 to 5 microns. This effect is explained by an increased power density produced by the photonic jet coupled to the active device layers through the photodetector mesas. The photocurrent gain provided by photonic jets is found to be in good agreement with the numerical modeling.
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Meemon, Panomsak. "Development of optical coherence tomography for tissue diagnostics." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4558.
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Endoscopic OCT utilizes a special miniature probe in the sample arm to access tubular organs inside the human body, such as the cardiovascular system, the lung, the gastrointestinal tract, the urinary tract, and the breast duct. We present an optical design of a dynamic focus endoscopic probe that is capable of about 4 to 6 micrometers] lateral resolution over a large working distance (i.e. up to 5 mm from the distal end of the probe). The dynamic focus capability allows integration of the endoscopic probe to GD-OCM imaging to achieve high resolution endoscopic tomograms. We envision the future of this developing technology as a solution to high resolution, minimally invasive, depth-resolved imaging of not only structure but also the microvasculature of in vivo biological tissues that will be useful for many clinical applications, such as dermatology, ophthalmology, endoscopy, and cardiology. The technology is also useful for animal study applications, such as the monitoring of an embryo's heart for the development of animal models and monitoring of changes in blood circulation in response to external stimulus in small animal brains.; However, the improvement in imaging speed of FD-OCT comes at the expense of a reduction in sensitivity to slow flow information and hence a reduction in detectable velocity range; 2) A structural ambiguity so-called 'mirror image' in FD-OCT prohibits the use of maximum sensitivity and imaging depth range; 3) The requirement of high lateral resolution to resolve capillary vessels requires the use of an imaging optics with high numerical aperture (NA) that leads to a reduction in depth of focus (DOF) and hence the imaging depth range (i.e. less than 100 microns) unless dynamic focusing is performed. Nevertheless, intrinsic to the mechanism of FD-OCT, dynamic focusing is not possible. In this dissertation, the implementation of PR-DOCT in a high speed swept-source based FD-OCT is investigated and optimized. An acquisition scheme as well as a processing algorithm that effectively extends the detectable velocity dynamic range of the PR-DOCT is presented. The proposed technique increased the overall detectable velocity dynamic range of PR-DOCT by about five times of that achieved by the conventional method. Furthermore, a novel technique of mirror image removal called 'Dual-Detection FD-OCT' (DD-FD-OCT) is presented. One of the advantages of DD-FD-OCT to Doppler imaging is that the full-range signal is achieved without manipulation of the phase relation between consecutive axial lines. Hence the full-range DD-FD-OCT is fully applicable to phase-resolved Doppler detection without a reduction in detectable velocity dynamic range as normally encountered in other full-range techniques. In addition, PR- DOCT can utilize the maximum SNR ratio provided by the full-range capability.; Microvasculature can be found in almost every part of the human body, including the internal organs. Importantly, abnormal changes in microvasculature are usually related to pathological development of the tissue cells. Monitoring of changes in blood flow properties in microvasculature, therefore, provides useful diagnostic information about pathological conditions in biological tissues as exemplified in glaucoma, diabetes, age related macular degeneration, port wine stains, burn-depth, and potentially skin cancer. However, the capillary network is typically only one cell in wall thickness with 5 to 10 microns in diameter and located in the dermis region of skin. Therefore, a non-invasive flow imaging technique that is capable of depth sectioning at high resolution and high speed is demanded. Optical coherence tomography (OCT), particularly after its advancement in frequency domain OCT (FD-OCT), is a promising tool for non-invasive high speed, high resolution, and high sensitivity depth-resolved imaging of biological tissues. Over the last ten years, numerous efforts have been paid to develop OCT-based flow imaging techniques. An important effort is the development of phase-resolved Doppler OCT (PR-DOCT). Phase-resolved Doppler imaging using FD-OCT is particularly of interest because of the direct access to the phase information of the depth profile signal. Furthermore, the high speed capability of FD-OCT is promising for real time flow monitoring as well as 3D flow segmentation applications. However, several challenges need to be addressed; 1) Flow in biological samples exhibits a wide dynamic range of flow velocity caused by, for example, the variation in the flow angles, flow diameters, and functionalities.; This capability is particularly useful for imaging of blood flow that locates deep below the sample surface, such as blood flow at deep posterior human eye and blood vessels network in the dermis region of human skin. Beside high speed and functional imaging capability, another key parameter that will open path for optical diagnostics using OCT technology is high resolution imaging (i.e. in a regime of a few microns or sub-micron). Even though the lateral resolution of OCT can be independently improved by opening the NA of the imaging optics, the high lateral resolution is maintained only over a short range as limited by the depth of focus that varies inversely and quadratically with NA. Recently developed by our group, 'Gabor-Domain Optical Coherence Microscopy' (GD-OCM) is a novel imaging technique capable for invariant resolution of about 2-3 micrometers] over a 2 mm cubic field-of-view. This dissertation details the imaging protocol as well as the automatic data fusion method of GD-OCM developed to render an in-focus high-resolution image throughout the imaging depth of the sample in real time. For the application of absolute flow measurement as an example, the precise information about flow angle is required. GD-OCM provides more precise interpretation of the tissue structures over a large field-of-view, which is necessary for accurate mapping of the flow structure and hence is promising for diagnostic applications particularly when combined with Doppler imaging. Potentially, the ability to perform high resolution OCT imaging inside the human body is useful for many diagnostic applications, such as providing an accurate map for biopsy, guiding surgical and other treatments, monitoring the functional state and/or the post-operative recovery process of internal organs, plaque detection in arteries, and early detection of cancers in the gastrointestinal tract.ID: 029050978; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 145-154).
Ph.D.
Doctorate
Optics and Photonics
39
Hu, Honghua. "Third Order Nonlinearity of Organic Molecules." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5310.
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The main goal of this dissertation is to investigate the third-order nonlinearity of organic molecules. This topic contains two aspects: two-photon absorption (2PA) and nonlinear refraction (NLR), which are associated with the imaginary and real part of the third-order nonlinearity (x3) of the material, respectively. With the optical properties tailored through meticulous molecular structure engineering, organic molecules are promising candidates to exhibit large third-order nonlinearities. Both linear (absorption, fluorescence, fluorescence excitation anisotropy) and nonlinear (Z-scan, two-photon fluorescence, pump-probe) techniques are described and utilized to fully characterize the spectroscopic properties of organic molecules in solution or solid-state form. These properties are then analyzed by quantum chemical calculations or other specific quantum mechanical model to understand the origins of the nonlinearities as well as the correlations with their unique molecular structural features. These calculations are performed by collaborators. The 2PA study of organic materials is focused on the structure-2PA property relationships of four groups of dyes with specific molecular design approaches as the following: (1) Acceptor-[pi]-Acceptor dyes for large 2PA cross section, (2) Donor-[pi]-Acceptor dyes for strong solvatochromic effects upon the 2PA spectra, (3) Near-infrared polymethine dyes for a symmetry breaking effect, (4) Sulfur-squaraines vs. oxygen-squaraines to study the role of sulfur atom replacement upon their 2PA spectra. Additionally, the 2PA spectrum of a solid-state single crystal made from a Donor-[pi]-Acceptor dye is measured, and the anisotropic nonlinearity is studied with respect to different incident polarizations. These studies further advance our understanding towards an ultimate goal to a predictive capability for the 2PA properties of organic molecules. The NLR study on molecules is focused on the temporal and spectral dispersion of the nonlinear refraction index, n2, of the molecules. Complicated physical mechanisms, originating from either electronic transitions or nuclei movement, are introduced in general. By adopting a prism compressor / stretcher to control the pulsewidth, an evolution of n2 with respect to incident pulsewidth is measured on a simple inorganic molecule –carbon disulfide (CS2) in neat liquid at 700 nm and 1064 nm to demonstrate the pulsewidth dependent nonlinear refraction. The n2 spectra of CS2 and certain organic molecules are measured by femtosecond pulses, which are then analyzed by a 3-level model, a simplified “Sum-over-states” quantum mechanical model. These studies can serve as a precursor for future NLR investigations.ID: 031001375; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Eric W. Van Stryland.; Co-adviser: David J. Hagan.; Title from PDF title page (viewed May 21, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 213-226).
Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
40
Broky, John. "Inverse Problems in Multiple Light Scattering." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5608.
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The interaction between coherent waves and material systems with complex optical properties is a complicated, deterministic process. Light that scatters from such media gives rise to random fields with intricate properties. It is common perception that the randomness of these complex fields is undesired and therefore is to be removed, usually through a process of ensemble averaging. However, random fields emerging from light matter interaction contain information about the properties of the medium and a thorough analysis of the scattered light allows solving specific inverse problems. Traditional attempts to solve these kinds of inverse problems tend to rely on statistical average quantities and ignore the deterministic interaction between the optical field and the scattering structure. Thus, because ensemble averaging inherently destroys specific characteristics of random processes, one can only recover limited information about the medium. This dissertation discusses practical means that go beyond ensemble averaging to probe complex media and extract additional information about a random scattering system. The dissertation discusses cases in which media with similar average properties can be differentiated by detailed examination of fluctuations between different realizations of the random process of multiple scattering. As a different approach to this type of inverse problems, the dissertation also includes a description of how higher-order field and polarization correlations can be used to extract features of random media and complex systems from one single realization of the light-matter interaction. Examples include (i) determining the level of multiple scattering, (ii) identifying non-stationarities in random fields, and (iii) extracting underlying correlation lengths of random electromagnetic fields that result from basic interferences. The new approaches introduced and the demonstrations described in this dissertation represent practical means to extract important material properties or to discriminate between media with similar characteristics even in situations when experimental constraints limit the number of realizations of the complex light-matter interaction.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
41
Sloanes, Trefor James. "Measurement and application of optical nonlinearities in indium phosphide, cadmium mercury telluride and photonic crystal fibres /." St Andrews, 2009. http://hdl.handle.net/10023/723.
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Sun, Peng. "Free-Standing Integrated Optics in Silicon." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1330528033.
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Akl, Ramsey. "Above bandgap thermo-optic coefficient measurements for direct bandgap materials." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 0.27Mb, 42 p, 2005. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1428187.
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Haakestad, Magnus W. "Optical fibers with periodic structures." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1494.
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This thesis concerns some experimental and theoretical issues in fiber optics. In particular, properties and devices based on photonic crystal fibers (PCFs) are investigated.
The work can be grouped into three parts. In the first part we use sound to control light in PCFs. The lowest order flexural acoustic mode of various PCFs is excited using an acoustic horn. The acoustic wave acts as a traveling long-period grating. This is utilized to couple light from the lowest order to the first higher order optical modes of the PCFs. Factors affecting the acoustooptic coupling bandwidth are also investigated. In particular, the effect of axial variations in acoustooptic phase-mismatch coefficient are studied.
In the second part of the thesis we use an electric field to control transmission properties of PCFs. Tunable photonic bandgap guidance is obtained by filling the holes of an initially index-guiding PCF with a nematic liquid crystal and applying an electric field. The electric field introduces a polarization-dependent change of transmission properties above a certain threshold field. By turning the applied field on/off, an electrically tunable optical switch is demonstrated.
The third part consists of two theoretical works. In the first work, we use relativistic causality, i.e. that signals cannot propagate faster than the vacuum velocity of light, to show that Kramers-Kronig relations exist for waveguides, even when material absorption is negligible in the frequency range of interest. It turns out that evanescent modes enter into the Kramers-Kronig relations as an effective loss term. The Kramers-Kronig relations are particularly simple in weakly guiding waveguides as the evanescent modes of these waveguides can be approximated by the evanescent modes of free space. In the second work we investigate dispersion properties of planar Bragg waveguides with advanced cladding structures. It is pointed out that Bragg waveguides with chirped claddings do not give dispersion characteristics significantly different from Bragg waveguides with periodic claddings.
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Ho, Tony Yatming. "Non-Reciprocal Wave Transmission in Integrated Waveguide Array Isolators." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5302.
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Non-reciprocal wave transmission is a phenomenon witnessed in certain photonic devices when the wave propagation dynamics through the device along one direction differs greatly from the dynamics along the counter-propagating direction. Specifically, it refers to significant power transfer occurring in one direction, and greatly reduced power transfer in the opposite direction. The resulting effect is to isolate the directionality of wave propagation, allowing transmission to occur along one direction only. Given the popularity of photonic integrated circuits (PIC), in which all the optical components are fabricated on the same chip so that the entire optical system can be made more compact, it is desirable to have an easily integrated optical isolator. Common free-space optical isolator designs, which rely on the Faraday effect, are limited by the availability of suitable magnetic materials. This research proposes a novel integrated optical isolator based on an array of closely spaced, identical waveguides. Because of the nonlinear optical properties of the material, this device exploits the differing behaviors of such an array when illuminated with either a high power or a low power beam to achieve non-reciprocal wave transmission in the forwards and backwards directions, respectively. The switching can be controlled electro-optically via an integrated gain section which provides optical amplification before the input to the array. The design, fabrication, characterization and testing of this optical isolator are covered in this dissertation. We study the switching dynamics of this device and present its optimum operating conditions. ?ID: 031001286; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Patrick LiKamWa.; Title from PDF title page (viewed February 26, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 103-110).
Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
46
Peceli, Davorin. "Absorptive and Refractive Optical Nonlinearities in Organic Molecules and Semiconductors." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5687.
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The main purpose of this dissertation to investigate photophysical properties, third order nonlinearity and free carrier absorption and refraction in organic materials and semiconductors. Special emphasis of this dissertation is on characterization techniques of molecules with enhanced intersystem crossing rate and study of different approaches of increasing triplet quantum yield in organic molecules. Both linear and nonlinear characterization methods are described. Linear spectroscopic characterization includes absorption, fluorescence, quantum yield, anisotropy, and singlet-oxygen generation measurements. Nonlinear characterization, performed by picosecond and femtosecond laser systems (single and double pump-probe and Z-scan measurements), includes measurements of the triplet quantum yields, excited-state absorption, two-photon absorption, nonlinear refraction and singlet and triplet-state lifetimes. The double pump-probe technique is a variant of the standard pump-probe method but uses two pumps instead of one to create two sets of initial conditions for solving the rate equations allowing a unique determination of singlet- and triplet-state absorption parameters and transition rates. The advantages and limitations of the the double pump-probe technique are investigated theoretically and experimentally, and the influences of several experimental parameters on its accuracy are determined. The accuracy with which the double pump-probe technique determines the triplet-state parameters improves when the fraction of the population in the triplet state relative to the ground state is increased. Although increased accuracy is in principle achievable by increasing the pump fluence in the reverse saturable absorption range, it is shown that the DPP is optimized by working in the saturable absorption regime. Two different approaches to increase intersystem crossing rates in polymethine-like molecules are presented: traditional heavy atom substitution and molecular levels engineering. Linear and nonlinear optical properties of a series of polymethine dyes with Br- and Se- atoms substitution, and a series of new squaraine molecules, where one or two oxygen atoms in a squaraine bridge are replaced with sulfur atoms, are investigated. A consequence of the oxygen-to-sulfur substitution in squaraines is the inversion of their lowest lying ??' and n?' states leading to a significant reduction of singlet-triplet energy difference and opening of an additional intersystem channel of relaxation. Experimental studies show that triplet quantum yields for polymethine dyes with heavy-atom substitutions are small (not more than 10%), while for sulfur-containing squaraines these values reach almost unity. Experimental results are in agreement with density functional theory calculations allowing determination of the energy positions, spin-orbital coupling, and electronic configurations of the lowest electronic transitions. For three different semiconductors: GaAs, InP and InAsP two photon absorption, nonlinear refraction and free carrier absorption and refraction spectrums are measured using Z-scan technique. Although two photon absorption spectrum agrees with the shape of theoretical prediction, values measured with picosecond system are off by the factor of two. Nonlinear refraction and free carrier nonlinearities are in relatively good agreement with theory. Theoretical values of the third order nonlinearities in GaAs are additionally confirmed with femtosecond Z-scan measurements. Due to large spectral bandwidth of femtosecond laser, three photon absorption spectrum of GaAs was additionally measured using picosecond Z-scan. Again, spectral shape is in excellent agreement with theory however values of three photon absorption cross sections are larger than theory predicts. ?Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
47
El, Dirani Houssein. "Development of high quality silicon nitride chips for integrated nonlinear photonics." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEC027/document.
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La montée exponentielle du trafic de données liée au développement de l’interconnexion entre objets et personnes sur la toile nécessite de nouvelles technologies. Au cours de la dernière décennie, les peignes de fréquences optiques ont révolutionné le secteur des télécommunications, ouvrant la voie à une transmission de données à un débit de données auparavant inaccessible. Mis à part le domaine des télécommunications, les peignes de fréquences optiques ont été avantageusement exploités dans d’autres domaines comme la détection optique, la détection chimique, les horloges optiques… L'efficacité du phénomène de mélange à quatre ondes, qui sous-tend la génération des peignes de fréquences, dépend de manière significative des pertes par propagation dans les guides d’ondes optiques et, par conséquent, de la rugosité de ces derniers. De plus, l'absorption intrinsèque du matériau réduit l'efficacité des phénomènes non linéaires tout en contribuant à l’atténuation du signal lumineux dans le milieu optique de propagation. Grâce à la maturité des procédés de fabrication dits CMOS, la rugosité peut être réduite en optimisant la gravure, tandis que l’absorption peut être réduite par des traitements thermiques. L'utilisation d'un matériau CMOS permet donc une fabrication à faible coût et la co-intégration avec d’autres dispositifs optoélectroniques sur la même puce. Le nitrure de silicium sur isolant est une plateforme prometteuse pour la génération de peignes de fréquences optiques grâce à la faible absorption à deux photons dans ce matériau par rapport au silicium cristallin. Cependant, le nitrure présente une absorption dans la bande des télécommunications relié à la présence des liens moléculaires N-H. Tandis que des recuits à haute température ont été utilisés pour réduire le contenu en hydrogène du film et démontrer avec succès la génération de peignes de fréquence, ces procédés rendent la co-intégration monolithique de ces dispositifs en nitrure de silicium avec une optoélectronique à base de silicium très difficile, réduisant ainsi considérablement sa compatibilité avec les autres matériaux CMOS. Dans cette thèse, nous décrivons la conception, la fabrication et les caractérisations de circuits photoniques non-linéaires en nitrure de silicium sans recuit. En particulier, nous avons mis au point un procédé de fabrication de films de Si3N4 d'une épaisseur de 740 nm, sans utilisation de recuit et avec une maitrise de la gestion des contraintes typiquement associées à ce type de matériau pour l’optique non linéaire. Cette approche offre une compatibilité de fabrication technologique avec la photonique sur silicium. Des preuves expérimentales montrent que les micro-résonateurs utilisant de tels films de nitrure de silicium sans recuit sont capables de générer un peigne de fréquence s'étendant sur 1300-2100 nm via une oscillation paramétrique optique basée sur du mélange à quatre ondes. En allant encore plus loin, nous présentons également les travaux d’optimisation technologique portant sur des microrésonateurs en nitrure de silicium recuits avec des guides d’onde à fort confinement modal, qui nous ont permis d’atteindre des pertes de propagation record. Ces résultats ont été rendus possible grâce à une optimisation fine des étapes de gravure des guides d’onde ainsi qu’à l'utilisation de traitements thermiques-chimiques efficaces. Cette nouvelle approche nous a permis de démontrer par ailleurs des sources de peignes de fréquences intégrées sur puce utilisant des résonateurs en nitrure de silicium couplés par aboutement à un laser III-V DFB utilisé comme une pompe. Cette preuve de concept prouve la validité de notre plateforme de circuits photoniques non-linéaires en Si3N4 pour la réalisation de peignes de fréquences optiques ultra-compacts à faible consommationThe data traffic need for ultra-high definition videos as well as for the mobile data continues to grow. Within the last decade, optical frequency combs have revolutionized the telecommunications field and paved the way for groundbreaking data transmission demonstrations at previously unattainable data rates. Beside the telecommunications field, optical frequency combs brought benefits also for many other applications such as precision spectroscopy, chemical and bio sensing, optical clocks, and quantum optics. The efficiency of the four-wave mixing phenomenon from which the optical frequency comb arises critically depends on the propagation losses and consequently on the device roughness induced by the lithography and the etching processes. In addition, the bulk material absorption reduces the efficiency of the nonlinear phenomena. By using state-of-the-art complementary metal oxide semiconductor processes, the roughness can be reduced thanks to the maturity of the manufacturing, while the material bulk absorption can be reduced by thermal treatments. In addition, using a CMOS material enables a low-cost fabrication and the co-integration with electronic devices into the same chip. Silicon-nitride-on-insulator is an attractive CMOS-compatible platform for optical frequency comb generation in the telecommunication band because of the low two-photon absorption of silicon nitride when compared with crystalline silicon. However, the as deposited silicon nitride has a hydrogen related absorption in the telecommunication band. Although high-temperature annealing has been traditionally used to reduce the hydrogen content and successfully demonstrate silicon nitride-based frequency combs, this approach made the co-integration with silicon-based optoelectronics elusive, thus reducing dramatically its effective complementary metal oxide semiconductor compatibility. In this thesis, we report on the fabrication and test of annealing-free silicon nitride nonlinear photonic circuits. In particular, we have developed a process to fabricate low-loss, annealing-free and crack–free Si3N4 740-nm-thick films for Kerr-based nonlinear photonics, featuring a full process compatibility with front-end silicon photonics. Experimental evidence shows that micro-resonators using such annealing-free silicon nitride films are able to generate a frequency comb spanning 1300-2100 nm via optical parametrical oscillation based on four-wave mixing. In addition, we present the further optimized technological process related to annealed silicon nitride optical devices using high-confinement waveguides, allowing us to achieve record-low losses. This was enabled via a carefully tailored patterning etching process and an annealing treatment particularly efficient due to the already low hydrogen content in our as-deposited silicon nitride. Such improved Si3N4 platform allowed us to demonstrate on-chip integrated Kerr frequency comb sources using silicon nitride resonators that were butt-coupled to a III-V DFB laser used as a pump source. This proof of concept proves the validity of our approach for realizing fully packaged compact optical frequency combs
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Frank, Ian Ward. "Integrated filters for the on-chip silicon photonics platform." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11205.
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We investigate the properties of integrated dielectric filters for the purposes of on-chip routing of photons. We started with the use of high quality factor tunable photonic crystal nanobeam cavities and moving on to examine a new class of reflection based reverse designed filters that maintain the footprint of a waveguide while allowing for arbitrary amplitude and phase response.Engineering and Applied Sciences
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Xu, Su. "Optical Fluid-based Photonic and Display Devices." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5585.
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Conventional solid-state photonic devices exhibit an ultra-high optical performance and durability, but minimal adaptability. Recently, optical fluid-based photonic and display devices are emerging. By dynamically manipulating the optical interface formed by liquids, the optical output can be reconfigured or adaptively tuned in real time. Such devices exhibit some unique characteristics that are not achievable in conventional solid-state photonic devices. Therefore, they open a gateway for new applications, such as image and signal processing, optical communication, sensing, and lab-on-a-chip, etc. Different operation principles of optical fluid-based photonic devices have been proposed, for instance fluidic pressure, electrochemistry, thermal effect, environmentally adaptive hydrogel, electro-wetting and dielectrophoresis. In this dissertation, several novel optical fluid-based photonic and display devices are demonstrated. Their working principles are described and electro-optic properties investigated. The first part involves photonic devices based on fluidic pressure. Here, we present a membrane-encapsulated liquid lens actuated by a photo-activated polymer. This approach paves a way to achieve non-mechanical driving and easy integration with other photonic devices. Next, we develop a mechanical-wetting lens for visible and short-wavelength infrared applications. Such a device concept can be extended to longer wavelength if proper liquids are employed. In the second part, we reveal some new photonic and display devices based on dielectrophoretic effects. We conceive a dielectric liquid microlens with well-shaped electrode for fixing the droplet position and lowering the operating voltage. To widen the dynamic range, we demonstrate an approach to enable focus tuning from negative to positive or vice versa in a single dielectric lens without any moving part. The possibility of fabricating microlens arrays with different aperture and density using a simple method is also proposed. Furthermore, the fundamental electro-optic characteristics of dielectric liquid droplets are studied from the aspects of operating voltage, frequency and droplet size. In addition to dielectric liquid lenses, we also demonstrate some new optical switches based on dielectrophoretic effect, e.g., optical switch based on voltage-stretchable liquid crystal droplet, variable aperture or position-shifting droplet. These devices work well in the visible and near infrared spectral ranges. We also extend this approach to display and show a polarizer-free and color filter-free display. Simple fabrication, low power consumption, polarization independence, relatively low operating voltage as well as reasonably fast switching time are their key features.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
50
Zheng, Juanjuan. "Design and fabrication of photonic crystal fibers for nonlinear microscopy /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?ECED%202008%20ZHENG.
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