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Reilly, Mark Alexander. "Integrated polymer waveguide optical amplifiers." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614010.
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Cao, Qiusheng. "Planar waveguide CO2 laser amplifiers." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/1224.
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Brown, Christian Thomas Alcuin. "Nd-doped crystal waveguide lasers and amplifiers." Thesis, University of Southampton, 1997. https://eprints.soton.ac.uk/394563/.
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This thesis presents the results of investigations into waveguide lasers and optical amplifiers fabricated in Nd-doped crystals. Laser operation of Nd3+ doped Ti:LiNbO3 around 900nm is reported. A threshold power of 26mW was obtained when the device was pumped with a Ti:Al2O3 laser operating around 814nm. The wavelength of the waveguide fundamental mode cut-off was altered by manipulation of the device fabrication parameters to induce higher propagation losses at the parasitic laser wavelength of 1.084µm and thus enhance lasing behaviour around 900nm. A 1.2W diode-pumped, Nd:Y3Al5O12 (Nd:YAG) waveguide optical amplifier has been demonstrated with a simple double pass geometry. Small signal gains as high as 28.4dB were observed along with extracted power efficiencies of up to 36%. Deviation from ideal performance is explained by reference to intense pumping effects and pump/signal overlap in the device. The coupling of diode-bars into planar waveguides for high power operation has been analysed. Using a lens array to couple the diode output into an Nd:YAG planar waveguide, an extremely compact, end pumped, device was constructed which had a slope efficiency of 40% with respect to incident pump power and a maximum output power of 1.5W for 6W of diode power. Fibre lens and proximity coupling scheme designs have also been examined. A Ti:Al2O3 face pumped LPE waveguide laser has been demonstrated. Nd:YAG on YAG, Nd:Gd3Ga5O12 on YAG and Nd:YAG on glass waveguides fabricated by thermal bonding have been studied. These structures had numerical apertures of 0.06, 0.74 and 0.82 respectively. The propagation losses, obtained from the laser performance, were found to be 0.7B/cm, 0.4dB/cm and 0.7dB/cm respectively.
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Cheung, Chun Tung Rutledge David B. "Waveguide packaging of quasi-optical grid amplifiers /." Diss., Pasadena, Calif. : California Institute of Technology, 2003. http://resolver.caltech.edu/CaltechETD:etd-05192003-161134.
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Meshkinfam, Peyman. "Erbium-ytterbium co-dopped ion-exchanged waveguide amplifiers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0029/MQ38696.pdf.
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Saini, Sajan 1973. "Gain effect waveguide optical amplifiers for Si microphotonics." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28885.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.<br>Includes bibliographical references (p. 288-294).<br>(cont.) Er-based gain. We reported the first infrared photoluminescence PL study of Er₂O₃ and found a 7 ms lifetime at 4 K, attributed to a metastable FCC or HCP phase. We showed the thermodynamically stable BCC crystal phase has PL emission lines at 1537 nm and 1550 nm, and metastable FCC and HCP crystal phases result in PL emission lines at 1542 nm and 1533 nm. Upconversion coefficient measurements on the BCC phase and 7 ms lifetime metastable phase gave values of 10⁻¹⁷ and 10⁻¹⁸ cm³/s, respectively. Comparison of room temperature absorption versus 4 K PL of Er₂O₃ and an SiO₂:Er reference showed the BCC phase to be the dominant volume fraction. The calculated WOA power requirements for 3 dB gain in the metastable phase were found to be 450 mW. We examined SiON and Si₃N₄ for high index difference ([delta]n=0.1-0.7) Er host materials. Samples were grown by sputtering, and we investigated the optical materials quality of this process by studying sputtered SiO₂:Er; we report a record co-sputtered SiO₂:Er room temperature lifetime of 14 ms. PL versus heat treatment results strongly indicate the nitride environment of Si₃N₄ favors a higher Er solubility and lower cooperative upconversion than the oxide environment of SiO₂. We measure a 2.4 ms radiative lifetime in co-sputtered Si₃N₄:Er, [approximately] 4x smaller than radiative lifetime reports in ion implanted Si₃N₄:Er PL samples; we attribute this enhancement to an optimized Er ligand field from the sputter process ...<br>Si Microphotonics is a micron-scale planar processing technology compatible with the fabrication tools of Si Microelectronics. The first demonstration of an integrated set of microphotonic devices replicating the function of an entire fiber optic link, dubbed a Planar Lightwave Circuit (PLC), is being developed to solve the Integrated Circuit (IC) interconnection bottleneck problem: the project proposes replacing time delaying metal interconnects with optical interconnects, i.e. a PLC integrated onto the IC chip. This work requires the development of compact micron-scale analogs to fiber optic link device elements. In this thesis, we take example from commercially available Erbium Doped Waveguide Amplifiers (EDWAs), to investigate the use of high Er concentration doped materials and device design optimization to create gain efficient Waveguide Optical Amplifiers (WOA) in the PLC, at 1.55 [micro]m light. We develop a waveguide index difference An scaling methodology with which to optimally design a WOA into as small a planar footprint as possible and using as little optical pump power as required. We observe that device gain efficiency and footprint have a power-law dependence, summarized in a cumulative Figure-of-Merit, of [delta]n²·⁶. This strong improvement in WOA performance is dependent on the requirement of strip waveguide propagation losses < 0.2 dB/cm, a requirement demonstrated in SiON waveguides. We conclude that a 10 mW-powered 3 dB or 30 dB gain WOA can be fit into a 425x425 [micro]m² or 3x3 mm² footprint, respectively, using an SiON [delta]n=0.155 Er-doped strip waveguide. The impact of [delta]n scaling shows the WOA to be feasible for dense PLCs and low cost planar EDWAs. We examined Er₂O₃ as a materials candidate for ultra-high<br>by Sajan Saini.<br>Ph.D.
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Ali, Muhammad Irshad. "Sol-gel routes to erbium doped waveguide amplifiers (EDWAs)." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/11098.
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The potential of new erbium doped materials has been assessed with the aim of enhancing and tailoring the emission properties of ER<sup>III</sup> ions (such as PL spectrum and lifetime) in pure and modified SiO<sub>2</sub> hosts through sol-gel methodologies. The main focus has been to investigate potential use of novel precursor, erbium triflate, in combination with different organophosphorus ligands, and aluminium co-dopants, for the synthesis of sol-gel thin films, bulk and power materials. This thesis describes two main approaches. In the first approach, sols were synthesised using standard sol-gel hydrolysis and condensation process. This was followed by the deposition of thin films by spin coating. After the deposition the films were thermally treated at high temperature to produce compact inorganic SiO<sub>2</sub> networks. Finally, the optical characterisation of the films has been studied. The films were optically inactive. The second approach consisted of synthesis of sol-gel bulk materials in the form of glasses and glass ceramics co-doped with Al<sup>III</sup> and P<sup>V</sup> ions, transparent glasses and glass ceramics incorporating Er<sup>III</sup> ions concentration as high as ~10 mol % were prepared containing active nanocrystallites of erbium phosphate in amorphous SiO<sub>2</sub> matrix. Optical characterisation of these glass ceramics has shown that broad and flat emission photoluminescence spectra of Er<sup>III</sup> ions with FWHM greater than 100 nm are obtained only in the materials containing ErPO<sup>4</sup> nanocrystals with average diameter of 4-5nm combined with a narrow and uniform size distribution. Visible upconversion was also detected in the Er-doped sol-gel SiO<sub>2</sub> powders under excitation at 800 and 980 nm. Excited state absorption (ESA) and energy transfer up-conversion (ETU) have been discussed as possible mechanism for visible up-conversion.
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Shankar, Ratnambikai. "Erbium/Ytterbium co-doped planar waveguide amplifiers, modeling and fabrication." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60495.pdf.
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Warburton, Toby James. "Lasers and amplifiers in bulk and planar waveguide oxide crystals." Thesis, University of Southampton, 1997. https://eprints.soton.ac.uk/399481/.
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This thesis reports the results of investigations into efficient, miniature solid state lasers and optical amplifiers in rare earth doped oxide crystals. Waveguides doped with the trivalent thulium ion were grown in YAG and YSO host crystals and lased, when optically pumped, at 2.012µm and 1.884µm, respectively. The Tm:YAG laser had absorbed power laser thresholds as low as 7mW and slope efficiencies as high as 68%. The planar devices were fabricated using the technique of liquid-phase epitaxy which produces waveguides of excellent optical quality and with very low propagation losses. High gain optical amplifiers have been demonstrated in Nd:YAG planar waveguides pumped by a Ti: sapphire laser and a diode laser. A small-signal gain of 28.4dB was obtained in a waveguide fabricated by liquid-phase epitaxy; in the same waveguide 290 mW of power was extracted for only ~550mW of absorbed pump power. A small-signal gain of 23.5dB was achieved in a Nd:YAG waveguide, fabricated by thermal bonding, for 250mW of absorbed pump power. Pumping directly into the upper laser manifold of a bulk Nd:YAG rod, at 869nm has produced a highly efficient laser on the quasi-three-level 946nm transition. The lower energy defect for a laser pumped in this manner relative to conventionally pumped Nd:YAG lasers should result in higher slope efficiencies and fewer thermal problems when pumped at high powers. Using such a pumping scheme a slope efficiency of 75% with respect to absorbed power was obtained.
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Madasamy, Pratheepan. "Fabrication and characterization of erbium doped waveguide amplifiers and lasers." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280304.
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Planar waveguide amplifiers and lasers were fabricated using Ag film ion exchange on Er³⁺/Yb³⁺ codoped phosphate glass. The performance of these amplifiers and lasers were studied and characterized. Silver film ion exchange process was thoroughly studied and a process suitable for fabrication of low loss waveguides on Er³⁺/Yb³⁺ codoped phosphate glass was developed. A transmission loss of 0.15 dB/cm was obtained in surface waveguides on phosphate glass. Planar waveguide amplifiers were fabricated on Er³⁺/Yb³⁺ codoped phosphate glass and characterized. A net gain of 7 dB in a sample of length 4.7 cm and gain/cm of 1.5 dB/cm were achieved. Single mode waveguide laser arrays pumped by single mode laser diodes were fabricated. Their performance was characterized in terms of the output power, spectrum of the laser, lasing wavelength dependence on the waveguide width and the relative intensity noise (RIN) of the laser. The tunability of the lasing wavelength to the desired wavelength, after waveguide fabrication, by annealing was demonstrated. A novel planar waveguide laser configuration for single-mode operation around 1550 nm using cost-effective multimode diode pumping was demonstrated. The laser was fabricated by Ag film ion exchange in a hybrid phosphate glass which has active and passive regions monolithically integrated in a single glass chip. Power of 54 mW at 1538 nm was measured from the single-mode output waveguide.
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Krishnaswamy, Madhu. "Modeling and fabrication of rare-earth-doped integrated optical waveguide amplifiers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0001/NQ29057.pdf.
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Laliotis, Athanasios. "Analysis and fabrication of homogenous, high concentration erbium doped waveguide amplifiers." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422283.
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Loh, William Ph D. Massachusetts Institute of Technology. "Analysis and characterization of slab-coupled optical waveguide amplifiers and lasers." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55124.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 136-140).<br>Semiconductor optical devices are important in the photonics industry due to their significant advantages in size, weight, and power consumption (SWAP) and to their capability for photonic integration. However, these devices traditionally suffer from low fiber coupling efficiency and have been limited to relatively low power applications. This thesis explores the potential of the slab-coupled optical waveguide (SCOW) semiconductor gain medium for use in high power optical amplifiers and external cavity lasers. The thesis begins by introducing the SCOW concept and describing the benefits of utilizing a low optical confinement design for high power operation. Detailed analysis and measurements of the output power, gain, and noise properties of slab-coupled optical waveguide amplifiers (SCOWAs) and slab-coupled optical waveguide external cavity lasers (SCOWECLs) are also presented. It will be shown that these devices not only exhibit Watt class output power with high coupling efficiency (> 90 %) but also demonstrate the capability for low noise operation.<br>by William Loh.<br>S.M.
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Haque, Talha. "Silicon-based Microwave/Millimeter-wave Monolithic Power Amplifiers." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31174.
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There has been increased interest in exploring high frequency (mm-wave) spectrum (particularly the 30 and 60 GHz ranges), and utilizing silicon-based technology for reduced-cost monolithic millimeter integrated circuits (MMIC), for applications such as WLAN, inter-vehicle communication (IVC) automotive radar and local multipoint distribution system (LMDS). Although there has been a significant increase in silicon-based implementations recently, this area still has significant need for research and development. For example, one microwave/mm-wave front-end component that has seen little development in silicon is the power amplifier (PA).
Two potential technologies exist for providing a solution for low-cost microwave/mm-wave power amplifiers: 1) Silicon-Germanium (SiGe) HBT and 2) Complementary metal-oxide semiconductor (CMOS). SiGe HBT has become a viable candidate for PA development since it exhibits higher gain and higher breakdown voltage limits compared to CMOS, while remaining compatible with BiCMOS technology. Also, SiGe is potentially lower in cost compared to other compound semiconductor technologies that are currently used in power amplifier design. Hence, this research focuses on design of millimeter-wave power amplifiers in SiGe HBT technology.
The work presented in this thesis will focus on design of different power amplifiers for millimeter-wave operating frequencies. Amplifiers present the fundamental trade-off between linearity and efficiency. Applications at frequencies highlighted above tend to be point-to-point, and hence high linearity is required at the cost of lowered efficiency for these power amplifiers. The designed power amplifiers are fully differential topologies based on finite ground coplanar waveguide (FGC) transmission line technology, and have on-chip matching networks and bias circuits. The selection and design of FGC lines is supported through full-wave EM simulations. Tuned single stub matching networks are realized using FGC technology and utilized for input and output matching networks.
Two 30-GHz range SiGe HBT PA designs were carried out in Atmel SiGe2RF and IBM BiCMOS 8HP IC technologies. The designs were characterized first by simulations. The performance of the Atmel PA design was characterized using microwave/mm-wave on wafer test measurement setup. The IBM 8HP design is awaiting fabrication. The measured results indicated high linearity, targeted output power range, and expected efficiency performance were achieved. This validates the selection of SiGe HBT as the technology of choice of high frequency point-to-point applications. The results show that it is possible to design power amplifiers that can effectively work at millimeter-wave frequencies at lower cost for applications such as mm-wave WLAN and IVC where linearity is important and required transmitted power is much lower than in cellular handset power amplifiers. Moreover, recommendations are made for future research steps to improve upon the presented designs.<br>Master of Science
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George, Mathew [Verfasser], Wolfgang [Akademischer Betreuer] Sohler, and Donat Josef [Akademischer Betreuer] As. "Ti:Tm:LiNbO 3 Waveguide amplifiers and lasers / Mathew George. Betreuer: Wolfgang Sohler ; Donat Josef As." Paderborn : Universitätsbibliothek, 2012. http://d-nb.info/1036553108/34.
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Eckner, Jürg. "Semiconductor optical amplifiers: optimization of polarization and monolithical integration in ridge waveguide bulk InGaAsP/InP /." Zürich, 1998. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=12792.
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Sohn, Jooyoung. "Photoreceivers for optical microwave transmission based on flip-chip integrated waveguide photodiodes and HEMT amplifiers." Aachen : Shaker, 2005. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014181292&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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BANERJEE, SIDDHARTHA. "OPTICAL PROPERTIES AND POPULATION STATISTICS OF ERBIUM IN OPTICALLY-PUMPED ERBIUM-DOPED ZINC SILICATE GERMANATE WAVEGUIDE AMPLIFIERS." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1100892919.
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Sohn, Jooyoung [Verfasser]. "Photoreceivers for Optical Microwave Transmission Based on Flip-Chip Integrated Waveguide Photodiodes and HEMT Amplifiers / Jooyoung Sohn." Aachen : Shaker, 2005. http://d-nb.info/1186581093/34.
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Banerjee, Siddhartha. "Optical properties and population statistics of erbium in optically pumped erbium doped zinc silicate germanate (ZSG) waveguide amplifiers." Cincinnati, Ohio : University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1100892919.
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Ahmad, Norhawati Binti. "Modelling and design of Low Noise Amplifiers using strained InGaAs/InAlAs/InP pHEMT for the Square Kilometre Array (SKA) application." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/modelling-and-design-of-low-noise-amplifiers-using-strained-ingaasinalasinp-phemt-for-the-square-kilometre-array-ska-application(b2b50fd8-0a13-4f71-b3f0-616ee4b2a82b).html.
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The largest 21st century radio telescope, the Square Kilometre Array (SKA) is now being planned, and the first phase of construction is estimated to commence in the year 2016. Phased array technology, the key feature of the SKA, requires the use of a tremendous number of receivers, estimated at approximately 37 million. Therefore, in the context of this project, the Low Noise Amplifier (LNA) located at the front end of the receiver chain remains the critical block. The demanding specifications in terms of bandwidth, low power consumption, low cost and low noise characteristics make the LNA topologies and their design methodologies one of the most challenging tasks for the realisation of the SKA. The LNA design is a compromise between the topology selection, wideband matching for a low noise figure, low power consumption and linearity. Considering these critical issues, this thesis describes the procedure for designing a monolithic microwave integrated circuit (MMIC) LNA for operation in the mid frequency band (400 MHz to 1.4 GHz) of the SKA. The main focus of this work is to investigate the potential of MMIC LNA designs based on a novel InGaAs/InAlAs/InP pHEMT developed for 1 µm gate length transistors, fabricated at The University of Manchester. An accurate technique for the extraction of empirical linear and nonlinear models for the fabricated active devices has been developed. In addition to the linear and nonlinear model of the transistors, precise models for passive devices have also been obtained and incorporated in the design of the amplifiers. The models show excellent agreement between measured and modelled DC and RF data. These models have been used in designing single, double and differential stage MMIC LNAs. The LNAs were designed for a 50 Ω input and output impedance. The excellent fits between the measured and modelled S-parameters for single and double stage single-ended LNAs reflects the accurate models that have been developed. The single stage LNA achieved a gain ranging from 9 to 13 dB over the band of operation. The gain was increased between 27 dB and 36 dB for the double stage and differential LNA designs. The measured noise figures obtained were higher by ~0.3 to ~0.8 dB when compared to the simulated figures. This is due to several factors which are discussed in this thesis. The single stage design consumes only a third of the power (47 mW) of that required for the double stage design, when driven from a 3 V supply. All designs were unconditionally stable. The chip sizes of the fabricated MMIC LNAs were 1.5 x 1.5 mm2 and 1.6 x 2.5 mm2 for the single and double stage designs respectively. Significantly, a series of differential input to single-ended output LNAs became of interest for use in the Square Kilometre Array (SKA), as it utilises differential output antennas in some of its configurations. The single-ended output is preferable for interfacing to the subsequent stages in the analogue chain. A noise figure of less than 0.9 dB with a power consumption of 180 mW is expected for these designs.
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Wächtler, Thomas. "Conception of an integrated optical waveguide amplifier." Thesis, Universitätsbibliothek Chemnitz, 2004. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200400976.
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The work provides an overview of different integrated optical amplifiers. Semiconductor optical amplifiers and fiber amplifiers are described, as well as devices that utilize non-linear effects, nanocrystalline materials, or photonic crystals. Dielectric materials that are doped with rare-earth ions are considered more thoroughly. After a review of the principles of their optical activity the general mechanisms of excitation and emission are described. Materials aspects regarding the spectral range, their fabrication and the solubility of the dopants follow. An erbium-doped alumina waveguide amplifier, reported earlier in the literature, is chosen as an example to demonstrate the feasibility of such components. A theoretical model of the population densities of the energy levels is derived for the simulation. By numerical methods the non-linear system of the rate equations is solved and the stability of the steady state is shown. The simulation of the amplifier demonstrates the dependence of the gain of both the excitation energy and the z-coordinate. Moreover, the superiority of an excitation wavelength of 980 nm compared to 1530 nm is shown. With the model the literature data could be reproduced<br>Die Arbeit gibt einen Überblick über verschiedene Möglichkeiten der Realisierung integriert-optischer Wellenleiterverstärker. Ausgehend von optischen Halbleiter- und Faserverstärkern werden einführend ebenso Anordnungen beschrieben, die nichtlineare Effekte sowie nanokristalline Materialien und photonische Kristalle nutzen. Besondere Bedeutung kommt dielektrischen Materialien zu, die mit optisch aktiven Dotanden, bevorzugt Seltenerdionen, versehen sind. Hierbei werden die Ursachen für die optische Aktivität der Lanthanide sowie die generellen Mechanismen der Anregungs- und Emissionsprozesse beschrieben. Aspekte der Materialauswahl, vor allem hinsichtlich des verwendeten Spektralbereiches sowie bezüglich ihrer Herstellung und der Löslichkeit der Dotanden schließen sich an. Anhand eines Literaturbeispiels wird die Realisierbarkeit eines erbiumdotierten Aluminiumoxid-Wellenleiterverstärkers demonstriert. Hierfür wird ein Modell zur Simulation der Besetzungsdichten der angeregten Energieniveaus abgeleitet und mittels numerischer Methoden das sich ergebende, nichtlineare System der Ratengleichungen gelöst, wobei besonders die Stabilität des stationären Besetzungszustandes herausgearbeitet wird. Die Simulation der Verstärkeranordnung zeigt zum einen die Abhängigkeit der Verstärkung von der z-Koordinate sowie der Pumpleistung; zum anderen wird deutlich, dass die Anregung bei 980 nm der Variante bei 1530 nm überlegen ist. Mit dem verwendeten Modell konnten die Literaturdaten reproduziert werden
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Wächtler, Thomas. "Conception of an integrated optical waveguide amplifier." [S.l. : s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11244014.
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KARAMSHUK, SVITLANA. "Organic sensitizers for application in photonic and photovoltaic devices." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/76622.
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With the increasing demand for reliable and efficient devices with minimal environmental impact, novel organic materials gain extreme interest in the research community and industry. In this work we present synthetic strategies towards new organic compounds as promising materials for dye sensitized solar cells (DSCs) and low-cost integrated optics along with the investigation of these materials in devices.
Despite the recent hype in the research community around DSCs, increasing efficiency of DSCs is still a challenge. In principle, one promising way to obtain DSCs with significantly enhanced efficiency lies in connecting an n-type photoelectrode (i.e. n-Dye/TiO2) with a p-type one (i.e. p-Dye/NiO) leading to a tandem cell composed by two serially connected photoactive electrodes, each contributing with its own photovoltage to the total photovoltage delivered by the cell. Applying such concept could theoretically lead to organic photovoltaic devices with up to 40% overall conversion yield. One of the main limitations in p-type systems, commonly based on NiO, arises from fast charge recombination between the photoinjected hole in NiO, and the reduced dye. Therefore it is crucially important to develop p-type chromophores which could produce a long-lived charge separated state and minimize back recombination.
We were thus triggered to explore new organic structures for potentially efficient chromophores for p-type devices, by considering that the intramolecular charge transfer, at the basis of efficient charge separation in donor-acceptor dyes, is strongly dependent on the electron-withdrawing ability of the acceptor. Herein we present charge separators based on organic push-pull systems of tryphenylamine donors and branched electron acceptors (SK2-3-4) based either on Dalton (SK2) or benzothidaziole acceptor groups (SK3-4) which were synthesized and characterized by steady state spectroscopic, electrochemical and computational means. All the dyes exhibit strong charge transfer bands in the visible regions with ground and excited state energetics which are favourable to the sensitization of NiO electrodes. The computational investigation revealed a clear directionality of the lowest excited state exhibiting a marked charge transfer character, shifting the electron density to the acceptor branches, an electronic situation which is favourable to the hole injection in p-type semiconductors. When tested in p-type DSCs the SK series was found capable to sensitize NiO electrodes. The charge recombination kinetics, probed by considering the charge transfer resistance at the NiO/electrolyte interface at a comparable chemical capacitance, showed that the dyes behaved similarly and that the higher Voc observed with the SK4 dye is ostensibly due to a positive shift of the valence band edge, consistent with the shift in the anodic current threshold observed in dark conditions.
The second part of this work is dedicated to synthesis and characterisation of metallo-organic materials for optoelectronic devices. Optical amplification plays crucial role in the transmission and manipulation of optical signals in modern telecomunications. Nowadays amplifiers, which rely on erbium ions in a glass matrix, suffer from difficulties in fabrication and the need of high pump power densities to produce gain. Here we show a newly synthesised series of organic fully halogenated optical amplifier materials.
We will compare the ability of materials with different halogen atoms in complexes with transition metals to provide population of triplets which together with the lack of CH or OH oscillators in the molecule, can be potentially used as an efficient chromophore to sensitise the erbium ions in a long-lifetime erbium complex. Finally by doping Er(FTPIP)3 with newly designed Zn and Co complexes, we aim to find differences in the lifetime emission from erbium at the important telecommunication wavelength of 1.5 μm.
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Ohtsuki, Tomoko 1960. "Rare-earth-doped glass waveguides for amplifiers and lasers." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282169.
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Several different glass materials were investigated for waveguide amplifier and laser applications, and the potential to realize practical devices with these materials were examined using waveguides fabricated by ion exchange processes. Channel waveguides in an erbium doped phosphate laser glass were fabricated by a dry silver-film ion exchange technique, and the effects of high Er³⁺ concentration were investigated in terms of Er³⁺ ion interactions and energy transfer from Yb³⁺ to Er³⁺. Cooperative upconversion coefficients of the ⁴I₁₃/₂ level,7.7±0.7x 10⁻¹⁹ cm³/sec and 9.3±0.7x10⁻¹⁹ cm³/sec, were obtained experimentally for Er³⁺ concentration of 1x10²⁰ cm³ in the bulk and waveguide samples, respectively. These values are one order of magnitude smaller than the ones reported for silica glass. The increase in the cooperative upconversion coefficient with the increase in Er³⁺ concentration was found to be small. The effects of cooperative upconversion on the gain performance were analyzed for different Er³⁺ concentrations using a theoretical model which adopted experimentally obtained parameters. Given the small cooperative upconversion coefficients in this glass, Er³⁺ concentrations potentially as high as 3.7x10²⁰ cm⁻³ were shown to be feasible by the modeling. This would result in a 12 dB gain with a 4 cm long waveguide for 150 mW pump power at 1.48 μm. The transfer efficiency from Yb3+ to Er³⁺ was found to be 95% or higher for samples with Er³⁺ concentrations of 1.9x10²⁰ cm⁻³, and 24x10²⁰ cm⁻³, even when the ratio of the concentrations, Yb/Er, is only about 1.2 and 2. Planar channel waveguides of rare-earth doped fluoride glass were demonstrated with single mode excitation and propagation loss below 3 dB/cm. The waveguide core was fabricated by Ag⁺-Na⁺ molten salt ion exchange process in a borosilicate glass (BGG31), and a Nd³⁺-doped ZBLAN glass was used as a cladding. A 0.45 dB signal amplification at 1.064 μm was observed in the fabricated 1cm long waveguide, and a 0.9 dB amplification is expected at the emission peak (1.049 μm). Modeling results suggest that 2.5 dB/cm is possible by improving surface flatness of the ZBLAN glass.
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Subramanian, Ananth. "Tantalum pentoxide waveguide amplifier and laser for planar lightwave circuits." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/301404/.
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A planar lightwave circuit (PLC) has been envisioned to provide a new generation of optical networks capable of delivering signal at high speed and bandwidth to the household. High index contrast (HIC) and optical gain in the same material system would substantially enhance integration of different optical devices in a small area and compensate for the losses in the system to realise low cost, dense multi-functional PLCs. This thesis investigates the use of tantala as a HIC material system for realising gain efficient Erbium doped waveguide amplifiers (EDWAs) and lasers to be used at 1.5 um wavelength, towards realising dense multi-functional PLCs. Slab waveguides were fabricated by magnetron sputter deposition under optimised conditions of a powder pressed, Er:Ta2O5 target onto an oxidized silicon substrate. Optimised sputtering process yielded a Er:Ta2O5 thin film with a refractive index of 2.105@ 1550 nm and a maximum erbium lifetime of 2.3 ms. Single mode rib waveguides were designed and the fabricated using photolithography and argon ion beam milling. A maximum propagation loss of 0.65 + or +- 0.05 dB/cm at 1600 nm was measured, the peak erbium absorption and emission cross-section was determined to be 4.8 +- 0.2 x 10-21 cm2 and 4.4 + or +- 0.2 x 10^-21cm2 respectively. Numerical modeling of Er:Ta2O5 based EDWA predicted a maximum gain of 4 dB/cm at 200 mW pump power, in a 5.4 cm long waveguide with an erbium concentration of 5.4 x 10 20 ions/cm3. Gain measurements were performed on a 2.3 cm long rib waveguide with a erbium concentration of 2.7 x 10 20 ions/cm3, at a pump power of 200 mW, and a net optical gain of 2.25 dB/cm peaking at 1531.5 nm was measured in a 2 <mu>um wide waveguide. The pump threshold with respect to the launched pump power was measured to be as low as 4.5 mW. The cavity was formed by affixing two mirrors at the end facets of the waveguides. Lasing was observed in a single longitudinal and transverse mode peaking between 1556 and 1560 nm. The lasing threshold of 14 mW with a slope efficiency of 0.3% was measured with respect to the launched power. Finally, a feasibility study for inscribing sub-micron grating structures on the Er:Ta2O5 waveguides were carried out using interferometric ablation. Gratings inscribed with 23 mJ/cm2 energy density and 1000 pulses yielded a maximum reflectivity of 11 dB for TE polarisation at 1505 nm. This feasibility study shows potential to realise integrated cavity line narrowed lasers and filters. Tantala has long been used for different photonic applications but gain at 1.5 um is demonstrated for the first time. The results presented in the thesis demonstrate that tantala due to its HIC, net optical gain and other inherent properties that it possesses have the potential to realise low cost, compact PLCs for the short haul networks.
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Harwood, Duncan William John. "Towards a 1.39 µm planar neodymium doped fluoride glass waveguide amplifier." Thesis, University of Southampton, 2000. https://eprints.soton.ac.uk/15495/.
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This thesis describes the steps towards the fabrication of a planar neodymium doped fluoride glass waveguide amplifier operating in the 1.3µm band. Approximations of the amplifier performance, combined with more detailed models of an integrated neodymium doped fluoroaluminate glass amplifier based on spectroscopic measurements from the bulk glass (Nd:ALF70), show that channel waveguides with propagation losses below 0.5dB/cm at the pump wavelength are needed to produce a device with a pump requirement of 200mW or less. In the absence of any fabrication technique available for fluoride glasses with this level of performance, the novel process of hot dip spin coating was developed for the fabrication of single mode Nd:ALF70 planar waveguides. The process is based on the inverted spin coating of molten glass onto a solid glass substrate and currently holds the record for the minimum propagation losses of less than 0.1dB/cm @ 1048nm in a fluoride glass waveguide measured in a 5 micron thick film. In order to capitalise on such exceptional waveguide performance, a new method for fabricating channel waveguides in fluoride glass thin films was developed based on direct UV writing of a negative index change using photothermal expansion. The process is based on generating a negative index change, via exposure to laser radiation at a wavelength of 244nm. The negative index change forms the lower refractive index 'cladding' on either side of the desired guiding region and is induced by a thermal mechanism generated by the large absorption of UV radiation by cerium ions doped into the slab guiding region. A maximum index range of close to 0.01 was produced for a 40µm thick unclad waveguide doped with 0.5mol% Ce3+ and an index change of approximately 2x10-3 was estimated for a 2.5mol% Ce3+ doped, 6 micron thick buried waveguide. Propagation losses of 0.1±0.1dB/cm @ 1048nm were determined by the Findlay-Clay technique for a 90µm wide multimode channel waveguide laser whilst an average value of 0.3±0.1dB/cm @ 1048nm was obtained for less multimode guides with an average width of 20µm. The best device performance has been characterised in a 1mol% Nd3+ doped 90µm wide and 6µm thick waveguide. Laser action at 1048nm has been observed with a slope efficiency of 27% for a 56% output coupler and a threshold pump Power of just 4mW. The threshold for laser action at 1317nm was 32mW for a 0.3% output coupler giving a slope efficiency of 2%. A peak internal gain of 1dB at 1317nm was achieved in this waveguide for a pump power of 100mW and suggests that the performance of optimised single mode guides should be close to that predicted by theory.
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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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Irannejad, Mehrdad. "Fabrication and characterization of glass-semiconductor integrated waveguide amplifier by pulsed laser deposition." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582113.
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The phosphate modified tellurite (PT) glasses were investigated for their potential applications of bulk glass and PLD films as glass-on-semiconductor integrated thin films for engineering a semiconductor pump source integrated waveguide amplification medium which can operate at a wavelength of 1500nm. High quality PT bulk glasses were used as PLD target for deposition of high quality thin films on the silica buffered GaAs substrate by using optimized deposition parameters; target-to- substrate distance, processing gas pressure, deposition temperature and laser energy. The propagation loss of the deposited films was measured as low as 2.3 dB/cm at a wavelength of 633 nm. The Er3+: 4I13I24I15/2 optical transition lifetime response was measured as 2.5 ms. However, a dramatic increasing in the measured lifetime value was recorded by increasing the deposition temperature. Although, deposited PT films shows crack free structure (in the 200nm range), the material transfer from the bulk target to the deposited films was observed to be non-stoichiometric transfer for rare-earth elements, and for host materials a stoichiometric transfer of the materials was observed. The effects of changing the ambient gas composition on the surface morphology of the deposited PLD film was investigated and it was found that using Oxygen-Helium gas mixture produce of a ceramic-like structure in deposited thin films. The ultrafast laser micromachining was used for thin film waveguide fabrication. However, strip loaded waveguide structures were carried out using conventional photolithography followed by reactive ion etching of Si3N4. Buried waveguide structure were fabricated using ultrafast laser micromachining technique in the bulk PT glasses, and maximum gain of 3.2 dB was recorded at the erbium peak for a 21 mm long waveguide using pump wavelength of 976 nm. However, for the ridge waveguide structure a non-inverted signal gain response with internal gain peak of 2.69 dB at 1565 nm for a 11 mm long waveguide was recorded in the deposited film on the silica substrate. Glass-on- semiconductor integrated waveguide structure was fabricated using Si3N4 as strip layer, and satisfactory ASE response to the 976 pump light was recorded.
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Soane, Alexander (Alexander Visotsky). "A 140 GHz gyro-amplifier using a confocal waveguide : theory and experimental results." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113937.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 139-147).<br>This thesis reports on the theory, design, and experimental investigation of a gyrotron travelling-wave-tube (TWT) amplifier at 140 GHz. The gyro-TWT uses the HE06 mode of a confocal geometry as its operating mode. The linear and nonlinear theory of the confocal waveguide is presented, along with a quasi-optical approach for describing the modes of a confocal waveguide. Both the equations of motion and the mode excitation equation are derived in detail. A beamlet code is introduced as a tool for calculating the linear and nonlinear gain of the azimuthally asymmetric confocal modes that interact with the electron beam with an annular distribution of electron guiding centers. This code has been successfully benchmarked against the code MAGY for azimuthally symmetric cases, and extends the capabilities of nonlinear gyroamplifier theory to configurations that lack azimuthal symmetry. The gyro-TWT experimental setup is presented in detail. Quasi-optical mode converters were designed, fabricated, and tested, ultimately achieving a coupling of -3 dB into the HE06 mode. The source of competing, parasitic oscillations was identified and addressed by the addition of dielectric loading attached to the side of the open geometry of the confocal waveguide. The improvements to the gyro-TWT system allowed for zero-drive stable operation at currents up to 3 A. The design frequency of 140.0 GHz was successfully amplified with 35 dB circuit gain and a -3 dB bandwidth of 1.2 GHz from a 48 kV, 3 A electron beam with a beam pitch factor of 0.64 and a perpendicular velocity spread of 6%. The gyro-TWT produced 550 W at 140.0 GHz under the same operating conditions. During experimental testing, the pulse length used was 2 microseconds. The performance of the confocal gyro-TWT suggests that it may be a candidate for application to Dynamic Nuclear Polarization (DNP) Nuclear Magnetic Resonance (NMR) experiments.<br>by Alexander Visotsky Soane.<br>Ph. D.
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Hudgins, Robert Anthony. "Photonic Applications of Rare Earth Doped TEOS Based Silica Thin Films and Waveguides." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054758007.
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Kaysir, Md Rejvi. "Novel luminescent solar concentrator utilizing stimulated emission." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16477.
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Luminescent Solar Concentrators (LSCs) are an emerging technology that aims primarily to reduce the cost of photovoltaic (PV) power generation, with great potential for building-integrated photovoltaics (BIPV) system. Commercial realization of these devices is mainly hampered by reabsorption loss. This work describes a novel method of reducing the reabsorption as well as improving the directional emission utilizing stimulated emission, rather than only spontaneous emission as in standard LSCs, by using a seed laser. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire area of the LSC panel, modifying the emission spectrum of the photoexcited luminophores such that it is spectrally narrower, at a wavelength that minimizes reabsorption and allows a net gain in the system, and is directed towards a small PV cell, anticipated to be ~ 1 mm2. A fraction of the PV cell’s output power is fed back to the seed laser; i.e. the system acts as a closed loop system. This thesis reports the design and working principle of a stimulated-LSC (s-LSC) and the development of a mathematical model to identify important physical parameters for the practical realization. Also, a novel method to characterize the luminophores for the s-LSC system is developed using a parameter called ‘stimulated gain coefficient.' Finally, this concept has been explored with the known photostable Perylene Red (PR) dyes for the proof of principle. The experimental results are well-matched with the model except for the gain saturation with a comparatively small seed laser signal power. To investigate this gain saturation, two approaches were taken: investigating (i) spectral hole burning and (ii) triplet state absorption. None of the existing luminophores investigated show the required characteristics for the s-LSC system. However, there is a plenty of room for the innovation of luminophores to realize a practical s-LSC system.
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De, Leon Arizpe Israel. "Amplification of Long-Range Surface Plasmon-Polaritons." Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19790.
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Surface plasmon-polaritons are optical surface waves formed through the interaction of photons with free electrons at the surface of metals. They offer interesting applications in a broad range of scientific fields such as physics, chemistry, biology, and material science. However, many of such applications face limitations imposed by the high propagation losses of these waves at visible and near-infrared wavelengths, which result mainly from power dissipation in the metal.
In principle, the propagation losses of surface plasmon-polaritons can be compensated through optical amplification. The objective of this thesis is to provide deeper insights on the physics of surface plasmon-polariton amplification and spontaneous emission in surface plasmon-polariton amplifiers through theoretical and experimental vehicles applied (but not necessarily restricted) to a particular plasmonic mode termed long-range surface plasmon-polariton.
On the theoretical side, the objective is approached by developing a realistic theoretical model to describe the small-signal amplification of surface plasmon-polaritons in planar structures incorporating dipolar gain media such as organic dye molecules, rare-earth ions, and quantum dots. This model takes into account the inhomogeneous gain distribution formed near the metal surface due to a non-uniform excitation of dipoles and due to a position-dependent excited-state dipole lifetime that results from near-field interactions between the excited dipoles and the metal. Also, a theoretical model to describe the amplified spontaneous emission of surface plasmon-polaritons supported by planar metallic structures is developed. This model takes into account the different energy decay channels into which an exited dipole located in the vicinity of the metal can relax. The validity of this model is confirmed through experimentation.
On the experimental side, the objective is approached by providing a direct experimental demonstration of complete loss compensation in a plasmonic waveguide. The experiments are conducted using the long-range surface plasmon-polariton supported by a symmetric thin gold waveguide incorporating optically pumped organic dye molecules in solution as the gain medium. Also, an experimental study of spontaneous emission in a long-range surface plasmon-polariton amplifier is presented. It is shown that this amplifier benefits from a low spontaneous emission into the amplified mode, which leads to an optical amplifier with low noise characteristics. The experimental setup and techniques are explained in detail.
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Forni, Federico. "Controllo ottico automatizzato di circuiti fotonici integrati: Progettazione, realizzazione e valutazione." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/6473/.
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In this report a new automated optical test for next generation of photonic integrated circuits (PICs) is provided by the test-bed design and assessment. After a briefly analysis of critical problems of actual optical tests, the main test features are defined: automation and flexibility, relaxed alignment procedure, speed up of entire test and data reliability. After studying varied solutions, the test-bed components are defined to be lens array, photo-detector array, and software controller. Each device is studied and calibrated, the spatial resolution, and reliability against interference at the photo-detector array are studied. The software is programmed in order to manage both PIC input, and photo-detector array output as well as data analysis. The test is validated by analysing state-of-art 16 ports PIC: the waveguide location, current versus power, and time-spatial power distribution are measured as well as the optical continuity of an entire path of PIC. Complexity, alignment tolerance, time of measurement are also discussed.
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Straka, Petr. "Ultrazvukový drtič konkrementů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219202.
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This thesis is focused on the methodes of crushing kidney’s concrements with continual wave for the frequency 27 kHz and the intensity of ultrasound 10 W/cm2. The main aim is design of the ultrasound head with layer converter and design circuitry. First part of this work describes physical principle of ultrasound, ultrasound waves and methods by which could be remove kidney’s concretions. Practical part of this work is focused on compreshive design of ultrasound crushing system. In the introdiction is analyzed the proposal of applicator and the next step decscribing proposal excitation generator. The work contains results of simulation which was done on proposal curcuit, drawings of scheme, list of components and drawing of PCB.
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Janse, van Rensburg Christo. "A SiGe BiCMOS LNA for mm-wave applications." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/26501.
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A 5 GHz continuous unlicensed bandwidth is available at millimeter-wave (mm-wave) frequencies around 60 GHz and offers the prospect for multi gigabit wireless applications. The inherent atmospheric attenuation at 60 GHz due to oxygen absorption makes the frequency range ideal for short distance communication networks. For these mm-wave wireless networks, the low noise amplifier (LNA) is a critical subsystem determining the receiver performance i.e., the noise figure (NF) and receiver sensitivity. It however proves challenging to realise high performance mm-wave LNAs in a silicon (Si) complementary metal-oxide semiconductor (CMOS) technology. The mm-wave passive devices, specifically on-chip inductors, experience high propagation loss due to the conductivity of the Si substrate at mm-wave frequencies, degrading the performance of the LNA and subsequently the performance of the receiver architecture. The research is aimed at realising a high performance mm-wave LNA in a Si BiCMOS technology. The focal points are firstly, the fundamental understanding of the various forms of losses passive inductors experience and the techniques to address these issues, and secondly, whether the performance of mm-wave passive inductors can be improved by means of geometry optimising. An associated hypothesis is formulated, where the research outcome results in a preferred passive inductor and formulates an optimised passive inductor for mm-wave applications. The performance of the mm-wave inductor is evaluated using the quality factor (Q-factor) as a figure of merit. An increased inductor Q-factor translates to improved LNA input and output matching performance and contributes to the lowering of the LNA NF. The passive inductors are designed and simulated in a 2.5D electromagnetic (EM) simulator. The electrical characteristics of the passive structures are exported to a SPICE netlist which is included in a circuit simulator to evaluate and investigate the LNA performance. Two LNAs are designed and prototyped using the 13μ-m SiGe BiCMOS process from IBM as part of the experimental process to validate the hypothesis. One LNA implements the preferred inductor structures as a benchmark, while the second LNA, identical to the first, replaces one inductor with the optimised inductor. Experimental verification allows complete characterization of the passive inductors and the performance of the LNAs to prove the hypothesis. According to the author's knowledge, the slow-wave coplanar waveguide (S-CPW) achieves a higher Q-factor than microstrip and coplanar waveguide (CPW) transmission lines at mm-wave frequencies implemented for the 130 nm SiGe BiCMOS technology node. In literature, specific S-CPW transmission line geometry parameters have previously been investigated, but this work optimises the signal-to-ground spacing of the S-CPW transmission lines without changing the characteristic impedance of the lines. Optimising the S-CPW transmission line for 60 GHz increases the Q-factor from 38 to 50 in simulation, a 32 % improvement, and from 8 to 10 in measurements. Furthermore, replacing only one inductor in the output matching network of the LNA with the higher Q-factor inductor, improves the input and output matching performance of the LNA, resulting in a 5 dB input and output reflection coefficient improvement. Although a 5 dB improvement in matching performance is obtained, the resultant noise and gain performance show no significant improvement. The single stage LNAs achieve a simulated gain and NF of 13 dB and 5.3 dB respectively, and dissipate 6 mW from the 1.5 V supply. The LNA focused to attain high gain and a low NF, trading off linearity and as a result obtained poor 1 dB compression of -21.7 dBm. The LNA results are not state of the art but are comparable to SiGe BiCMOS LNAs presented in literature, achieving similar gain, NF and power dissipation figures.<br>Dissertation (MEng)--University of Pretoria, 2012.<br>Electrical, Electronic and Computer Engineering<br>unrestricted
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Jouanno, Jean-Marc. "Amplification optique dans des guides d'ondes réalises par échange d'ions dans des verres phosphates dopes par des terres rares." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0013.
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Les amplificateurs optiques realises a partir de fibres dopees par des ions erbiums ont fait, grace a leurs bonnes performances, fortement evoluer les systemes de transmission a fibre optique. Nous en avons transpose les principes pour realiser des composants actifs d'optique integree sur des verres dopes par des terres rares. Cette technologie permet en effet une meilleure compacite et l'insertion simultanee de fonctions variees. Nous presentons les resultats obtenus dans des guides fabriques par echange ionique dans des verres phosphates. Les ions de terres rares, inclus des la synthese du materiau, y presentent des sections efficaces elevees et peuvent etre portes a une concentration de quelques pourcents en poids sans induire de reduction importante de la duree de vie de leur niveau metastable. Leurs caracteristiques spectroscopiques sont preservees apres l'echange d'ions. Les guides obtenus sont monomodes aux longueurs d'onde de pompe et de signal. Enterres, ils presentent de faibles pertes de propagation. En utilisant un dopage au neodyme, nous avons realise des amplificateurs a une longueur d'onde voisine de 1,05 micron ainsi qu'une source laser de faible seuil et de bonne efficacite de conversion de puissance. A l'aide d'un modele, nous avons pu estimer l'influence de l'addition de photons par transfert d'energie due a la concentration elevee de dopants. Nous avons egalement releve les gains autour de 1,3 micron. Ils sont limites par l'absorption a partir du niveau metastable et la faible probabilite d'emission. Nous avons modelise et realise des amplificateurs optiques a 1,5 micron en effectuant un co-dopage par des ions erbium et ytterbium. Nous avons mesure un gain net de 6 db sur des guides de 44 mm de long et nous avons pu mettre en evidence l'importance du confinement du mode guide. Ces resultats peuvent etre largement ameliores en optimisant les caracteristiques geometriques des guides et la concentration de dopants. Ils montrent que la technologie de l'echange d'ions constitue aujourd'hui une excellente marche d'acces a une utilisation plus large des dispositifs d'optique integree
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Ratovelomanana, Frédéric. "Contribution à la réalisation de circuits intégrés optoélectroniques de commutation spatiale ou de transposition de longueur d'onde." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0092.
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Les travaux presentes ici concernent les telecommunications optiques multicolores large bande. Ces travaux decrivent la realisation de circuits integres photoniques sur inp pour la commutation spatiale ou la transposition de longueur d'onde. Ces travaux se basent sur la technologie a ruban enterre sur inp permettant d'integrer de facon monolithique un guide passif faible perte avec un amplificateur optique semiconducteur. On decrit d'abord les methodes de modelisation des composants : indice effectif, galerkin et beam propagation. On detaille une technologie d'integration optoelectronique : integration guide/amplificateurs et transformateurs de modes guide/fibre (reduction des pertes de couplage a -3. 0 db par interface). On rapporte les performances de nouveaux commutateurs spatiaux avec des coupleurs directionnels ou des amplificateurs (portes optiques) : en particulier un diffuseur/combinateur monolithique un-vers-quatre (un gain fibre-fibre minimum de 1. 0 db, une sensibilite a la polarisation inferieure a 1. 0 db). On decrit differentes solutions possibles de technologies de transposition de longueur d'onde. On rapporte les caracteristiques des transpositeurs a modulation de gain xgm ou de phase xpm. Pour les transpositeurs xpm : - une grande dynamique, sans penalite, sur le taux d'erreur a 10 gb/s - une transmission sur les longues distances (10 gb/s sur 60 km avec une penalite de 1. 0 db) - une amelioration sur le taux d'extinction de 7 db a 2. 5 gb/s. On decrit des ameliorations pour transpositeurs xpm : de nouvelles structures passives de distribution energetique, une amelioration du couplage guide/amplificateur (3. 0 db par interface, un nouveau gain fibre-fibre, estime a 19 db) et l'insertion d'un dephaseur electrique (une penalite negative de -10 db a 2. 5 gb/s, avec dephaseur). Le manuscrit s'acheve par la presentation des perspectives a venir en technologie a ruban enterre.
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Palma, Giuseppe. "Design of microlaser in medium infrarer wavelengnth range for biomedicine and environmental monitoring." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S017/document.
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Les micro-résonateurs optiques comptent parmi les dispositifs les plus importants en photonique. Les résonateurs WGM sont assez particuliers. Il s'agit de composant présentant une symétrie circulaire comme c'est le cas des sphères, des anneaux, des disques et des tores. Les résonateurs WGM présentent un facteur de qualité exceptionnel et un volume modal très faible. Ces appareils peuvent être utilisés dans plusieurs domaines, notamment la télédétection, le filtrage optique et l'optique non linéaire. D'autres applications sont possibles en biologie, médecine, spectroscopie moléculaire, surveillance environnementale, astronomie et astrophysique grâce à l'exploitation du rayonnement moyen infrarouge. Les micro-résonateurs optiques comportent un grand nombre de transitions vibrationnelles qui agissent comme des «empreintes» pour de nombreuses molécules organiques permettant le développement d'applications spectroscopiques innovantes et de nouveaux capteurs. Il convient de noter que l'atmosphère de la terre est transparente au niveau des deux fenêtres de transmission atmosphérique. La première est comprise entre 3 et 5 μm et la seconde entre 8 et 13 μm, ce qui rend possible des applications telles que la détection d'explosifs à distance ainsi que le brouillage de communication confidentielles. La large fenêtre de transparence en verres de chalcogénures dans le domaine spectral infrarouge rend envisageable le développement de nombreuses applications. Les verres de chalcogénure sont caractérisés par une bonne résistance mécanique et une durabilité chimique suffisante dans l'eau et l'atmosphère. Par ailleurs, l'indice de réfraction élevé, le rendement quantique élevé, l'énergie de phonon faible et la solubilité importante des terres rares permettent des émissions dans le domaine spectral du moyen IR. Dans cette thèse, la conception de dispositifs innovants en chalcogénure pour des applications utilisant le moyen infrarouge est étudiée en utilisant un code d'ordinateur personnel formé de façon aléatoire. Les appareils reposent sur des trois types de micro-résonateurs : les microsphères, les micro-disques et les microbulles. Les résonateurs WGM sont efficacement excités à l'aide de fibres nervurées et de guides d'ondes optiques de forme conique. Le nouveau procédé de conception est développé en utilisant la méthode d'optimisation par essaims particulaires (PSO). Elle permet de maximiser le gain d'un amplificateur reposant sur une microsphère d'émission laser dopée à l'erbium à 4,5 μm. Une technique innovante permettant de caractériser les propriétés spectroscopiques de la terre rare intégrant la recherche électromagnétique en mode WGM grâce à l'algorithme PSO a été développée. Les valeurs récupérées sont entachées d’une erreur inférieure à celle prévue par les instruments de mesure ayant un coût élevé. Des applications intéressantes peuvent être obtenues en excitant le micro-résonateur avec une fibre conique présentant deux LPG identiques sur les côtés. En effet, les FLP peuvent sélectionner le couplage de modes de fibre avec le résonateur WGM. En utilisant différentes paires de FLP identiques, opérant dans différentes bandes de longueurs d'onde, il est possible de coupler de façon sélective différents résonateurs à l'aide de la même fibre optique. Un code informatique aléatoire a été développé et validé. Il a démontré la faisabilité d'un capteur de microbulles de glucose. Un microdisque en terre rare dopé est étudié pour obtenir une source de lumière compacte et économique dans l'infrarouge moyen. Un code informatique est développé afin de simuler un micro-disque de terre rare dopé et associé à deux guides d'ondes nervurés, un pour le signal et l'autre pour la pompe. Le modèle est validé à l'aide d'un micro-disque dopée à l'erbium émettant à 4,5 μm. Ce dispositif très prometteur pour des applications dans le moyen infrarouge est obtenu en utilisant un micro-disque de praséodyme dopé émettant à 4,7 μm<br>Optical micro-resonators represent one of the most important devices in photonics. A special kind is constituted by the WGM resonators, i.e. devices with circular symmetry such as spheres, rings, disks and toroids. They are characterized by very small dimensions, exceptionally quality factor and very low modal volume becoming a valuable alternative to the traditional optical micro-resonators, such as Fabry-Pérot cavities. These devices allow applications in several fields, such as sensing, optical filtering and nonlinear optics. In particular, different applications in biology and medicine, molecular spectroscopy, environmental monitoring, astronomy and astrophysics are feasible in Mid-Infrared wavelength range. For example, it includes a lot of strong vibrational transitions that act as “fingerprints” of many bio-molecules and organic species allowing the develop of innovative spectroscopic applications and novel sensors. In addition, the earth's atmosphere is transparent in two atmospheric transmission windows at 3–5 μm and 8–13 μm and then applications such as remote explosive detection, e.g. in airports and for border control, and covert communication systems are feasible. The wide transparency window of chalcogenide glasses in Mid-Infrared makes possible the development of several devices. Chalcogenide glasses are characterized by good mechanical strength and chemically durability in water and atmosphere. Furthermore, the high refractive index, high quantum efficiency, the low phonon energy and high rare-earth solubility enables the emissions at long wavelengths.In this thesis, the design of innovative chalcogenide devices for applications in Mid-Infrared is investigated using an ad-hoc home-made computer code. The devices are based on three kinds of micro-resonators: microspheres, micro-disks and microbubbles. The WGM resonators are efficiently excited by using tapered fiber and ridge waveguides. A novel design procedure is developed using the particle swarm optimization approach (PSO). It allows to maximize the gain of an amplifier based on an erbium-doped microsphere lasing at 2.7 μm.An innovative technique in order to characterize the spectroscopic properties of rare-earth is developed integrating the WGM electromagnetic investigation with PSO algorithm. The method is based on two subsequent steps: in the first one, the geometrical parameters are recovered, in the second one, the spectroscopic parameters. The recovered values are affected by an error less than that provided by high-cost measurement instruments. Furthermore, the procedure is very versatile and could be applied to develop innovative sensing systems.Interesting applications could be obtained exciting the micro-resonator by a tapered fiber with two identical LPGs on the sides. Indeed the LPGs can select the fiber modes coupling with the WGM resonator. Using different pairs of identical LPGs operating in different wavelength bands, it is possible to selective couple different micro-resonators by using the same optical fiber. An ad-hoc computer code is developed and validated and it demonstrated the feasibility of a microbubble glucose sensor.In order to obtain a compact and cost-saving light source in Mid-Infrared, rare-earth doped micro-disk are investigated. A computer code is developed in order to simulate a rare-earth doped micro-disk coupled to two ridge waveguide, one at signal wavelength and the other one at pump wavelength. The model is validated using an erbium-doped micro-disk emitting at 4.5 μm. A very promising device for application in Mid-Infrared is obtained using a praseodymium-doped micro-disk emitting at 4.7 μm
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Viallet, Benoît. "Conception d'un amplificateur optique à 1,3 (micron)m : spectroscopie de couches minces de LaF3 dopé Nd3+ et développement de procédés technologiques innovants." Toulouse 3, 2004. http://thesesups.ups-tlse.fr/21/.
Full textAbstract:
L'ion Nd3+ est un candidat potentiel pour réaliser un amplificateur optique à 1,3æm. Nous proposons une structure guide d'onde conçue à partir d'une couche mince de trifluorure de lanthane (LaF3) dopé néodyme (Nd3+) et intégrant un filtre par réseau de Bragg incliné. Nous avons caractérisé certaines propriétés spectroscopiques du LaF3:Nd3+ telles que la polarisation de l'émission à 1,3æm et l'effet de la concentration en ions Nd3+. La structure développée est originale de par l'utilisation d'un polymère pour réaliser les fonctions optiques passives et du LaF3:Nd3+ monocristallin comme matériau actif. Pour la fabriquer nous avons développé des technologies génériques permettant de réaliser des fonctions optiques bas coût : la nanoimpression, le polisciage et des traitements de surface. Finalement, nous avons modélisé l'amplificateur et déterminé les conditions à respecter pour optimiser le gain et le rendement du composant<br>Nd3+ ion is a potential candidate to realize an optical amplifier at 1. 3æm. A structure based on a thin layer of lanthanum trifluoride (LaF3) doped with neodymium (Nd3+) and including a tilted Bragg grating filter is proposed. Some spectroscopic parameters, such as the polarisation of 1. 3æm emission and the effects of Nd3+ concentration have been characterized. The proposed structure is inventive by some points, for exemple, the association of a polymer material to make passive optical functions and monocrystalline Nd3+: LaF3 as an active material. Generic technologies for the low cost fabrication of optical functions such nanoimprint lithography, poli-dicing, and surface treatments has been developed. The amplifier has been modelled and conditions to obtain a high gain and high efficiency have been defined
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Rameix, Armelle. "Réalisation et caractérisation de nouveaux guides d'ondes pour applications laser à 2 microns." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0176.
Full textAbstract:
L'epitaxie en phase liquide a permis de realiser des guides planaires emettant a temperature ambiante autour de 2 microns. Les materiaux etudies ont ete le yag (y3al5o12) et le yso (y2sio5) dopes par un ion terre rare tm3+. Ce memoire decrit les conditions necessaires pour l'obtention de couches de bonne qualite. Il met notamment en avant le fait que les conditions de croissance du yso sont beaucoup plus severes que celles du yag (plage de sursaturation plus petite, vitesse de croissance plus faible). Les differentes caracterisations effectuees ont montre la qualite des guides realises, notamment les performances laser qui ont ete obtenues. Les resultats obtenus pour le yag:tm confirment la bonne adaptation des guides a un pompage par diode. Un effet laser a ete obtenu pour les guides de yso:tm en pompant avec un laser saphir:titane. Ce sont les premiers resultats laser obtenus pour des guides planaires de yso:tm. L'epitaxie en phase liquide est une technique qui permet de realiser des guides planaires. Toutefois pour certaines applications l'utilisation de guides de largeur limitee est plus interessante. Nous avons donc developpe des procedes de fabrication de guides de largeur limitee. Deux techniques differentes sont exposees dans ce memoire: l'une faisant appel a des procedes de micro-usinage, que nous avons baptise polisciage, et la seconde basee sur un principe de gravure chimique. Les resultats obtenus sont prometteurs et pourraient etre utilises pour de futures applications (guides d'ondes laser, amplificateurs)
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Le, Luyer Yann. "Mise au point d'une technologie silice dopée erbium en optique intégrée pour l'amplification vers 1,5 µm." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0184.
Full textAbstract:
L'application conjointe des principes de l'amplification optique et de l'optique integree permet la realisation d'amplificateurs plus compacts et susceptibles d'etre associes a d'autres composants optiques sur un meme substrat. Nous decrivons la mise au point d'une technologie en silice dopee erbium sur silicium pour l'amplification vers 1,5 m. Nous detaillons en particulier l'etape de depot de la couche guidante par pulverisation cathodique et l'etape de gravure. Les parametres de depot ont ete optimises pour obtenir des guides planaires homogenes en indice et epaisseur. Ces guides presentent de plus de faibles pertes de propagation. Par ailleurs, l'etude de la gravure de notre materiau nous a permis de determiner la chimie de gravure adequate, conduisant a une amelioration du profil de gravure et a une reduction de la rugosite des guides, source de pertes par diffusion. Les proprietes de luminescence de nos guides ont ete etudiees. Les resultats obtenus demontrent l'interet de notre technologie pour l'amplification. Toutefois, la duree de vie de l'erbium, qui influence directement le gain potentiel, depend largement du procede d'elaboration. Par exemple, l'etape de recouvrement suivie d'un recuit, entraine la diffusion d'hydrogene vers la couche guidante, ce qui degrade la dure de vie. Un gain de plusieurs db a ete mesure. Ce resultat sera largement ameliore par l'optimisation des caracteristiques de l'amplificateur optique integre, telles que la concentration en erbium, la structure du guide ou ses pertes de propagation.
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Bruynooghe, Stéphane. "Étude de l'élaboration par voie sol-gel de structures guidantes SiO2/Si pour applications en optique intégrée." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0166.
Full textAbstract:
Ce travail traite de l'elaboration de structures guidantes sio#2/si a l'aide du procede sol-gel pour des applications en optique integree. La methodologie utilisee consiste en un suivi systematique de l'influence des conditions operatoires d'elaboration sur le comportement structural et optique des materiaux sol-gel, l'objectif etant l'optimisation de leurs performances. L'analyse bibliographique nous a permis de mettre en evidence l'interet de la technologie sol-gel pour le depot de films minces. Neanmoins, par cette technologie, l'elaboration de couches d'epaisseur micrometrique indispensables a la fabrication des guides d'onde, est delicate en raison de l'apparition de microfissures. En premier lieu, nous avons souligne l'importance d'un choix judicieux des parametres d'ordre chimique des solutions liquides de depart et avons concentre nos efforts sur l'obtention de couches minces optiquement guidantes. Les nombreuses techniques de caracterisation employees ont montre le lien etroit entre la microstructure et les proprietes optiques de nos depots sol-gel. En second lieu, la comprehension et la maitrise des phenomenes de contraintes generees au sein des films minces nous ont permis de realiser des couches d'epaisseur superieure au micron par multidepot. Les guides d'onde planaires ainsi realises revelent des pertes optiques de propagation inferieures a 0,2 db/cm dans la gamme de longueur d'onde comprise entre 1,2 et 1,7 m. En gravant ces guides, nous avons obtenu des guides de largeur limitee dont les pertes de propagation s'elevent a 0,77 db/cm a la longueur d'onde de 1,3 m. Enfin, nous avons presente une evaluation du procede sol-gel pour la realisation de dispositifs amplificateurs en optique integree. Les resultats obtenus sur les films minces sont tres prometteurs quant a l'elaboration de structures guidantes amplificatrices.
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Orignac, Xavier. "Fabrication et caractérisation de guides d'ondes sol-gel dopés terres-rares pour la réalisation d'amplificateurs optiques intégrés." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0014.
Full textAbstract:
Des amplificateurs sont necessaires a la regeneration du signal dans les lignes de transmission a grandes distances. Les amplificateurs optiques permettent de conserver la bande passante des systemes de transmission. Ils sont d'ores et deja disponibles commercialement sous forme de fibres dopees erbium, mais occupent un volume important et ne permettent pas la combinaison de plusieurs fonctions. Une alternative peut etre envisagee en transposant les principes des fibres dopees erbium a des amplificateurs integres. Un marche potentiel de grande ampleur existe pour de tels composants. Cette these est une premiere tentative de fabrication de tels amplivateurs par le procede sol-gel, dans une matrice vitreuse de sio#2-tio#2. Une premiere partie pose la problematique de l'etude et expose les parametres a optimiser : il faut augmenter le temps de vie du niveau metastable et la concentration d'auto-extinction des ions erbium, diminuer l'attenuation des guides, et controler l'epaisseur et l'indice des depots sol-gel. Dans une deuxieme partie, le processus de fabrication des guides est decrit et chaque etape du processus est analysee de facon a etudier son influence sur les parametres a optimiser. Dans la troisieme partie, on montre comment le processus de fabrication est oriente pour obtenir la meilleure qualite de guide possible. Les resultats obtenus sont presentes. Une etude preliminaire a ete effectue avec du neodyme. Une concentration d'auto-extinction de 1% atomique en neodyme et un temps de vie de fluorescence de 375 s a faible concentration sont atteints dans des guides plan. Avec l'erbium, la concentration d'auto-extinction est de 0. 6 % atomique, et un temps de vie de 6 ms est trouve a faible concentration. Une premiere mesure de gain sur des guides canaux donne 3 db de gain interne a 1531 nm. Le gain est constant sur 25 nm. Le procede sol-gel est une alternative aux technologies deja existantes (fhd et pecvd) pour l'integration d'amplificateurs optiques sur silicium. Ses capacites a fournir des amplificateurs de bonne qualite devraient etre mises en evidence par des etudes complementaires. Des solutions sont proposees.
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Broquin, Jean-Emmanuel. "Étude de guides d'onde dopés terres rares en optique intégrée sur verre en vue de réaliser un amplificateur optique." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0202.
Full textAbstract:
Le developpement des telecommunications optiques a entraine un besoin grandissant en composants actifs. La realisation de composants integres utilisant des verres dopes avec des terres rares est une solution interessante pour repondre a ce besoin. L'utilisation de verres fluores sous la forme de fibres optiques a permis de realiser des amplificateurs optiques de tres bonne qualite, l'emploi de tels verres en optique integree planaire semble donc tres prometteur. Dans ce rapport, nous presentons l'etude que nous avons menee pour realiser des guides d'ondes par echange d'ions dans des substrat de verres fluores big et zbla. Pour mener a bien notre travail, nous avons mis au point une procedure technologique propre aux verres fluores puis nous avons caracterise les guides ainsi obtenus. L'utilisation d'un echange anionique od/f a permis d'obtenir les premier guides d'onde monomode en optique integree planaire sur verre fluore. Cependant, une optimisation des parametres technologiques de realisation des guides est encore necessaire pour diminuer les pertes par propagation qui sont encore de l'ordre de 3db/cm. La mesure des proprietes spectroscopiques des ions nd#3#+ incorpores dans le verre a permis de demontrer l'influence nefaste des ions od sur la duree de vie du niveau metastable des ions actifs presents dans le guide. Une solution a ete proposee grace a l'utilisation d'ions ci pour remplacer les ions od. D'apres les premiers resultats obtenus, le comportement des ions actifs est meilleur avec ce type d'echange mais les pertes par propagation sont encore trop elevee pour permettre de reaslier un amplificateur optique. Finalement, pour permettre de realiser des amplificateurs optiques performants alliant de faibles pertes a de bonnes performances des ions de terres rares, nous avons propose et demontre une structure hybride active-passive. Cette structure, composee d'un guide passif realise par echange d'ions et d'une couche active guidante, devrait permettre a terme de concilier les avantages des technologies de type couches minces avec ceux des technologies de type echanges d'ions.
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Cheung, Chun Tung. "Waveguide Packaging of Quasi-Optical Grid Amplifiers." Thesis, 2003. https://thesis.library.caltech.edu/1867/1/final_master.pdf.
Full textAbstract:
Quasi-optical amplifiers combining the output powers of hundreds of transistors have demonstrated the capability to deliver more than 10 Watts of power at millimeter wave frequencies. However, these amplifiers are large and expensive to manufacture. In this work, we attempt to find a compact, low-cost approach using metallic waveguide to package a grid amplifier. This thesis details the design and implementation of a grid amplifier packaged in waveguide. Frequency and time-domain simulation methods are used to calculate the field flatness and the small signal gain of the amplifier. Four different active grids packaged in waveguide will be reported. The first grid, operating at Ka-band, is fed with a waveguide and radiates its output into free space. The amplifier chip design was previously measured in free-space. This work demonstrates a small signal gain of 7 dB with output power of 5.5 W at 3-dB compression. The performance is similar to the same grid design measured in free-space. A second Ka-band grid amplifier packaged in waveguide for both input and output gives a small signal gain of 6 dB. The 3-dB compressed output power is 670 mW while the same amplifier measured in free-space gave 1.2 W output power. In order to further verify our active grid and packaging design methods, a V-band single-stage monolithic grid amplifier was designed and fabricated. A transmission grid amplifier and a reflection grid amplifier using this chip were fabricated. Both amplifiers have 2 dB small-signal gain at 58 GHz. In order to increase small-signal gain, a two-stage monolithic grid amplifier was designed and fabricated. A reflection approach was used to package this chip. Measured small-signal gain was 2.7 dB at 82 GHz.
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Yan, Kunlun. "Rare-earth ion doped chalcogenide waveguide amplifiers." Phd thesis, 2018. http://hdl.handle.net/1885/162514.
Full textAbstract:
Chalcogenide glass waveguide devices have received a great deal
of attention worldwide in the last few years on account of their
excellent properties and potential applications in mid-infrared
(MIR) sensing and all-optical signal processing. Waveguide
propagation losses, however, currently limit the potential for
low power nonlinear optical processing, and the lack of suitable
on chip integrated MIR sources is one of the major barriers to
integrated optics based MIR sensing. One approach to overcome the
losses is to employ rare-earth ion doped waveguides in which the
optical gain can compensate the loss, in such a way that the
conversion efficiency of nonlinear effects is increased
significantly. For infrared applications, the long wavelengths
potentially attainable from rare-earth ion transitions in
chalcogenide hosts are unique amongst glass hosts. New rare-earth
ion doped chalcogenide sources in the MIR range could benefit
molecular sensing, medical laser surgery, defence etc. Despite
these promising applications, until now, no one has succeeded in
fabricating rare-earth ion doped chalcogenide amplifiers or
lasers in planar devices.
This work develops high quality erbium ion doped chalcogenide
waveguides for amplifier and laser applications. Erbium ion doped
As2S3 films were fabricated using co-thermal evaporation. Planar
waveguides with 0.35 dB/cm propagation loss were patterned using
photolithography and plasma etching on an erbium ion doped As2S3
film with an optimised erbium ion concentration of 0.45x1020
ions/cm3. The first demonstration of internal gain in an erbium
ion doped As2S3 planar waveguide was performed using these
waveguides. With different film deposition approaches, promising
results on intrinsic lifetime of the Er3+ 4I13/2 state were
achieved in both ErCl3 doped As2S3 films (2.6 ms) and radio
frenquency sputtered Er3+:As2S3 films (2.1 ms), however, no
waveguide was fabricated on these films due to film quality
issues and photopumped water absorption issues.
The low rare-earth ion solubility of As2S3 is considered the main
factor limiting its performance as a host. Gallium-containing
chalcogenide glasses are known to have good rare-earth ion
solubility. Therefore, a new glass host material, the Ge-Ga-Se
system, was investigated. Emission properties of the bulk glasses
were studied as a function of erbium ion doping. A region between
approximately 0.5 and 0.8 at% of Er3+ ion was shown to provide
sufficient doping, good photoluminescence and adequate lifetime
to envisage practical planar waveguide amplifier devices. Ridge
waveguides based on high quality erbium ion doped Ge-Ga-Se films
were patterned. Significant signal enhancement at 1540 nm was
observed and 50 % erbium ion population inversion was obtained,
in waveguides with Er3+ concentration of 1.5x1020 ion/cm3. To the
Author's knowledge, this is the highest level of inversion ever
demonstrated for erbium ions in a chalcogenide glass host and is
an important step towards future devices operating at 1550 nm and
on the MIR transitions of erbium ions in chalcogenide glass
hosts. Photoinduced absorption loss caused by upconversion
products in the waveguides is the remaining hurdle to achieving
net gain. Further research is needed to find suitable
compositions that possess high rare-earth ion solubility whilst
avoiding the detrimental photoinduced losses.
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Suh, Jae Woo. "Selectively Erbium Doped Titanium Diffused Optical Waveguide Amplifiers in Lithium Niobate." 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8897.
Full textAbstract:
Selectively erbium (Er) doped titanium (Ti) in-diffused optical waveguide amplifiers on lithium niobate (LiNbO3) substrate have been fabricated and characterized in the wavelength regime around λ = 1.53μm using counter-directional pumping at λP = 1.48μm. LiNbO3 waveguide amplifiers are desirable for providing gain in optical circuit chips through integration with other optical elements on a single substrate. A prerequisite for achieving useful gain rests on the optimization of overlap between the incident guided optical signal mode distribution and the evolving emission from excited Er ions. The extent of overlap can be controlled by adjusting fabrication parameters.
Fabrication parameters for Er-doped Ti in-diffused waveguide amplifiers of useful optical gain have been optimized by diffusing selective patterns of vacuum-deposited 17nm-thick erbium film at 1100˚C for 100 hours into LiNbO3, and integrating with 7μm-wide single mode straight channel waveguides formed by diffusing 1070Å thick titanium film into the LiNbO3. Small-signal gain characterization was carried out with a -30 dBm of transmitted input signal power at λS=1531nm with counter-directionally launched pump power ranging between 0 to 119mW at λP=1488nm, using TM polarization for both the signal and pump beams. At a maximum launched pump power of 119mW, a signal enhancement of 8.8dBm for 25mm-long erbium doped region, and 11.6dBm for 35mm-long erbium doped region were obtained. The corresponding calculated net gain values are 1.8dB and 2.8dB, for the 25mm-long and 35mm-long Er-doped regions, respectively.
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Weng, Tzung-Cheng, and 翁宗誠. "Analysis of Waveguide Bending Loss and Quantum-dot Semiconductor Optical Amplifiers." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/cgr578.
Full textAbstract:
碩士<br>國立中山大學<br>光電工程研究所<br>96<br>In this thesis, it mainly studies the performance characteristics of the bending losses in semiconductor waveguides and the quantum dots semiconductor optical amplifier. We used InP-subtract and InGaAlAs /InAlAs multiple quantum wells epitaxial wafer grown by MBE as our material(λg=1.41μm). We had successfully fabricated a series of bending strip-loaded waveguides. On the quantum dots semiconductor optical amplifier, symmetric InGaAlAs/GaAs quantum well structure is used to fabricate the optical waveguide. We have established an automatic optical measurement system to measure the device characteristics more accurately.
Design respect of bending waveguide, we design a series of radius, is 60μm, 80μm, 110μm, 170μm,and 260μm respectively, and utilize Fabry-Perot resonant, measurement and estimate the loss of bending waveguide in quantity. We find the bending waveguide loss as radius for 260μm and contain deeply etching process was quite equal to straight waveguide loss.
On the quantum dots semiconductor optical amplifier, we design a single mode waveguide and a broad area waveguide to compare the difference of their electron-hole combination situation. A single mode waveguide with longer cavity length had better combination situation than shorter (C311 of cavity length 4000μm ,0.00066μW *A/cm2). And the broad area waveguide had more better combination situation to single mode waveguide (C311 of cavity width 150μm, length 4000μm , 0.0966μW *A/cm2). For the gain to the pump signal, C311 singe mode waveguide (emission peak:1211nm,pump signal:1260nm) could get a gain about 3.56dB；and C374 singe mode waveguide (emission peak:1255nm,pump signal:1260nm) could get a gain about 6.1dB.
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Chen, Chih-Chiarng, and 陳志強. "Simulation on Counter-Propagation of Pulses in Multimode-Interference-Waveguide Amplifiers." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/56554717122765954542.
Full textAbstract:
碩士<br>國立臺灣大學<br>電信工程學研究所<br>87<br>The dynamics of two counter-propagating pulses in a multimode-interference-waveguide semiconductor optical amplifier (MMI SOA) is numerically studied using time-domain traveling-wave model. The single pulse propagation, two counter-propagating pulses incident on either the same lateral position or different lateral positions in an MMI SOA, and two counter-propagating pulses in a single-waveguide-mode SOA are numerical investigated. In some appropriately designed ring cavities, pulses can be repeatedly compressed after several round trips, as a result of the interplay between linear coupling and gain saturation in the MMI SOA. The characteristics of pulse collision in an MMI SOA are investigated by either launching identical pulses simultaneously, or launching identical pulses at different instants, or launching pulses of different pulse widths. It turns out that the collision of two counter-propagating pulses incident on the same lateral position in an MMI SOA provides the most nonlinear coupling effect. Especially, the amplified short pulses have an attractive force between each other that never appears in a single-waveguide-mode SOA.