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Rickman, Andrew George. "Silicon on insulator integrated optical waveguides". Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/843104/.
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This research project explored the potential of forming an integrated optics technology based on silicon core waveguides suitable for application in sensors and communications in the wavelength range 1.2 to 1.6 mum. Integrated optics has evolved around the use of compounds such as lithium niobate and III-V semiconductors due to their available electro-optic properties. By contrast silicon has received relatively little attention as its indirect band gap has prevented the fabrication of light sources in the material and its centrosymmetric crystal structure means that it has no useful linear electro-optic effect. The lack of a demonstrated low loss integrated optical waveguide compatible with single mode optical fibres has been a further limitation. However, these major drawbacks in silicon waveguide technology may be more than offset by the potential advantages of forming silicon integrated optical devices using well established silicon microelectronics fabrication methods. The project focused research on waveguiding in silicon-on-insulator (SOI) structures with the aim of developing a practical low loss waveguide in these structures and understanding the various loss mechanisms. In principle the optical absorption of pure crystalline silicon over the wavelength range of interest allows waveguides with losses less than 0.1 dB/cm to be formed. SOI material formed by ion implantation has been developed for microelectronic applications and provides a commercial source of a silicon planar waveguide structure with high quality interfaces and low defect density. The project studied waveguides based on this material. Initially planar waveguides with silicon thickness from 0.57 to 7.3 microns and buried oxide thickness of 0.07 to 0.4 microns were studied. Fabrication methods and structures were identified which allowed multi-microns planar SOI waveguides to be formed with losses less than the benchmark of 1 dB/cm. For these structures a buried oxide thickness of 0.4 microns was found to be sufficient to prevent substrate leakage loss. It has been concluded that the predominate loss mechanism is scattering of light at the silicon to buried oxide interface. Rib waveguides were formed in SOI following the insight into loss mechanisms gained in the planar waveguide studies. Optical rib waveguides with widths from 2.73 to 7.73 microns were formed in SIMOX (Separation by IMplantation of OXygen) based SOI structures consisting of a 4.32 micron thick surface silicon layer and a 0.398 micron buried oxide layer. The effect of waveguide width, bend radius, Y-junction splitting and interface roughness on loss and mode characteristics were studied at wavelengths of 1.15 and 1.523 microns. The experimental results support the hypothesis that certain rib dimensions can lead to single mode waveguides even though planar SOI waveguides of similar multi-micron dimension are multimode. The propagation losses of waveguides 3.72 microns wide were found to be 0.0 dB/cm and 0.4 dB/cm for the TE and TM modes respectively when measured at 1.523 microns. The measurement uncertainty was estimated to be +/-0.5 dB/cm. These results are thought to be the lowest loss measurements for silicon integrated optical waveguides reported to date. During the course of the project other researchers have demonstrated useful electro-optic properties in silicon semiconductor junctions based on the free carrier plasma dispersion effect and room temperature electroluminescence in silicon based junctions. The combination of these developments with the practical waveguide structure demonstrated in this project now makes the possibility of developing a practical silicon based integrated optics technology a reality.
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Bozeat, Robert John. "Thin film optical waveguides on silicon". Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320551.
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Spaargaren, Susan Marianne Rosemary. "Radiation effects on silica based waveguides". Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267942.
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Powell, Olly, i n/a. "Fabrication of Micro-Mirrors in Silicon Optical Waveguides". Griffith University. School of Microelectronic Engineering, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040719.115224.
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The conventional large radii bends used in large cross section silicon-on-insulator waveguides were replaced with novel wet etched corner mirrors, potentially allowing much smaller devices, therefore lower costs. If such corners had been based on reactive ion etch techniques they would have had the disadvantage of rougher surfaces and poor alignment in the vertical direction. Wet etching overcomes these two problems by providing smooth corner facets aligned precisely to the vertical {100} silicon crystallographic planes. The waveguides obtained had angled walls, and so numerical analysis was undertaken to establish the single mode condition for such trapezoidal structures. To show the relationship between fabrication tolerances and optical losses a three dimensional simulation tool was developed, based on expansion of the incident mode into plane waves. Various new fabrication techniques were are proposed, namely: the use of titanium as a mask for deep silicon wet anisotropic etching, a technique for aligning masks to the crystal plane on silicon-oninsulator wafers, a corner compensation method for sloping sidewalls, and the suppression of residues and pyramids with the use of acetic acid for KOH etching. Also, it was shown that isopropyl alcohol may be used in KOH etching of vertical walls if the concentration and temperature are sufficiently high. As the proposed corner mirrors were convex structures the problem of undercutting by high order crystal planes arose. This was uniquely overcome by the addition of some structures to effectively convert the convex structures into concave ones. The corner mirrors had higher optical losses than were originally hoped for, similar to those of mirrors in thin film waveguides made by RIE. The losses were possibly due to poor angular precision of the lithography process. The design also failed to provide adequate mechanisms to allow the etch to be stopped at the optimal time. The waveguides had the advantage over thin film technology of large, fibre-compatible cross sections. However the mirror losses must be reduced for the technology to compete with existing large cross section waveguides using large bends. Potential applications of the technology are also discussed. The geometry of the crystal planes places fundamental limits on the proximity of any two waveguides. This causes some increase in the length of MMI couplers used for channel splitting. The problem could possibly be overcome by integrating one of the mirrors into the end of the MMI coupler to form an L shaped junction.
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Arrand, Helena Frances. "Optical waveguides and components based on porous silicon". Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243510.
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Syahriar, Ary. "Passive integrated optical devices formed by electron beam irradiation of silica-on-silicon layers". Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481291.
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Hewitt, Peter Douglas. "Active optical devices in silicon-on-insulator rib waveguides". Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/843522/.
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Much progress has been made in the development of active silicon opto-electronic devices over the last 15 years. This is primarily due to the widely accepted belief that the free carrier effect is the most efficient optical modulation and switching mechanism in silicon, along with the potential advantages of combining optical and electronic devices onto a single silicon substrate rather than using discrete components. A study of the scientific literature shows that whilst numerous devices have been reported, few have been seriously optimised. In the literature, devices have consisted primarily of two or three terminal devices based around a rib waveguide. The three terminal devices are fewer in number but generally perform better. Conversely, two terminal devices have received a little more attention in terms of producing faster devices. Therefore, this work provides an in depth analysis of the performance of p+-i-n+ diodes when configured as optical modulators, with the aim of improving both the device DC and transient performance characteristics. The primary DC performance characteristic is the current required to achieve a given phase change and the transient performance characteristics are measured in terms of the device rise and fall times. These characteristics have been studied with variations in geometrical and fabrication based parameters such as the position and doping concentration of the contacts, the aspect ratio of the rib waveguides, and the overall dimensions. The key result from the modelling is that the most efficient multi-micron size device is a three terminal device with high doping concentration, constant doping profiles and large diffusion depth doped regions located close to the rib edge. A theoretical device of this nature required a current of only 2.7mA for a ? radian phase shift with rise and fall times of 22ns and 2ns respectively. The best previously achieved was a device which theoretically required 4mA for a ? radian phase shift. Additionally, by including isolation trenches on either side of the doped regions the DC performance characteristics can be further improved by up to 74%. There are also advantages in reducing the dimensions of the devices to 1 micron or less. At these dimensions the DC and transient performance characteristics are improved by more than a further order of magnitude, hence requiring fractions of 1mA for a ? radian phase shift. Two of the most promising designs have been fabricated and experimentally analysed. Due to fabrication constraints the most efficient device was not fabricated. However, both two and three terminal devices were fabricated. The best device tested experimentally was a three terminal device that required a current of 14mA for a ? phase shift. The modelling and experimental results agree well therefore validating the modelling. Therefore we can be confident that the additional theoretical results for devices that could not be fabricated are reliable, and hence significant further improvements could be made by fabricating these devices. Likely roles for these types of devices are medium bandwidth modulators/switches and a variety of sensor applications.
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Timotijevic, Branislav. "Auto-regressive optical filters in silicon-on-insulator waveguides". Thesis, University of Surrey, 2007. http://epubs.surrey.ac.uk/844086/.
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The subject of the thesis is the modelling, design, fabrication and characterisation of single-stage and multi-stage resonators on Silicon-on-Insulator (SOI) strip and rib waveguides. The devices have been investigated with the aim to produce small and efficient wavelength selective elements that could one day be used in multiplexers, filters and other components of integrated optical circuits. Due to the complexity of devices and very often requirements of advanced simulation packages, most of the devices have been modelled (lambda = 1.55mum) through separate analyses of the components forming the filters. The study starts with the modelling of rib and strip waveguides aiming at the single-mode and zero-birefringent regime of operation, followed by the analysis of a directional coupler. The modelling suggests that the cross-sectional rectangular area of a strip waveguide should be smaller than 0.10mum2. Similarly, rib waveguides with a height of 1.35mum, and a waveguide width of 0.8mum or 1.0mum, could be used as basic single-mode and zero-birefringent elements for building relatively large rib waveguide based devices. The analysis of a directional coupler on strip waveguides has shown that a near-polarisation-independence regime is possible for waveguide separations below 0.20mum and waveguide widths in range 0.29 - 0.40mum, when a waveguide height is chosen to be 0.29mum or 0.34mum. Simplified z-transform models of filters have been employed to calculate values of the most relevant figures of merit such as Free Spectral Range (FSR), Full Width at Half Maximum (FWHM), Finesse (F) and Q-factor, and also to quantify the sensitivity of the transfer function to the changes of geometric parameters, coupling issues and thermal effects. Based on the modelling and information from test chips of previous students, 4 main designs grouped in 6 test chips have been proposed and fabricated in collaboration with the Intel Corporation Photonics research groups from San Jose and Jerusalem. Two designs were based on rib waveguide type devices and two on strip waveguide type devices. The goals in all cases were; polarisation insensitivity, single-mode behaviour, improvement of the FSR, shaping response by using various geometries, the possibility of tuning response by thermal means etc. Experimental results have shown improvement in the FWHM and FSR as expected for both strip and rib designs. An additional stage of multi-level, serially coupled racetrack resonator in rib waveguides has resulted in a decrease of the FWHM by more than 30% (6pm). Polarisation independence by using identical multiple serial-coupled rib racetracks has also been demonstrated. The FSR above 60nm have been reported for small strip resonators (radius of l.5mum) with good polarisation characteristics for rings which radius is near 3mum. To the author's knowledge this is the largest FSR yet reported for a silicon based ring resonator. There is also improvement of the spectral response of multiple Vernier rings, which, with some corrections in terms of side lobes appearing in the spectrum, may be used for designing devices with the FSR as large as 70nm.
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Ang, Tze Wei. "Optical grating couplers in silicon-on-insulator". Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843726/.
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The aim of this project is to fabricate highly efficient grating couplers in thin-film silicon-on-insulator (SOI) wafers, which have a silicon (Si) thickness of the order of 1 mum. These thin-film waveguides allow the development of higher speed Si optical modulators, sensors and vertical surface coupling for Si light emitting diodes (LEDs), Hence, SOI rectangular and blazed grating couplers were fabricated where the buried oxide layer in SOI was designed as a reflective layer. The former gratings were fabricated by electron beam lithography followed by reactive ion etching, while the latter gratings were fabricated by angled argon ion beam etching. Both types of grating were designed at the diffraction order of -1, for a wavelength of 1.3 mum. The fabricated rectangular gratings have grating heights of 0.14, 0.23, 0.30 and 0.44 mum and a pitch of 0.40 mum whereas the sawtooth blazed gratings have a grating depth of 0.08 mum and a period of 0.38 mum To our knowledge, no Si blazed gratings with a pitch of less than 500 nm have been fabricated before. The SOI rectangular grating couplers yield a maximum output efficiency of 71 +/- 5 % towards the superstrate, while the blazed grating couplers produce an output efficiency of 84 +/- 5 % towards the substrate. These experimental output efficiencies are the highest yet reported in SOI for each grating profile, respectively. In addition, an optical loss of 0.15 +/- 0.05 dB/cm of Unibond SOI was measured for the first time. Furthermore, the experimental output efficiencies of the grating couplers with various grating heights were found to be consistent with perturbation theory. Thus, our aim of designing and fabricating an highly efficient thin film SOI waveguide grating coupler has been achieved. These grating couplers may enhance the applications of integrated optics in Si, and may allow the development of devices such as those mentioned above.
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Johnston, Ian Ronald. "Near-infrared photodetectors and optical interconnects fabricated monolithically on silicon". Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241870.
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Sun, Yitao. "Effect of stress on silicon oxynitride optical waveguides and devices". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ62856.pdf.
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Spasojevic, Mina. "Nonlinear optical signal processing and tunable optical delays in silicon-on-insulator waveguides". Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119660.
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The continued trend of increasing demand for large communications bandwidths is placing great strain on today's communications technology. This underlines the need for improving capacities and scalability of the existing as well as the future transmission systems. Investigating the capabilities of different modulation formats presents one way of addressing the matter. This thesis explores the optical time-division (de)multiplexing (OTDM) modulation scheme and provides a platform for building an all-optical signal processing system in silicon-on-insulator (SOI) relying on OTDM. It demonstrates successful OTDM demultiplexing and tunable optical delays both implemented in silicon nanoscale optical devices. OTDM demultiplexing is carried out by exploiting the nonlinearities in silicon waveguides. It focuses on four wave mixing (FWM) phenomenon chosen for its great potential for very high data rates resulting from its instantaneous nature, in addition to the advantage of being transparent to modulation formats. The thesis demonstrates how all-optical OTDM demultiplexing can be achieved through a two step process, generation of continuously tunable delay line followed by demultiplexing process, with both steps implemented in the same silicon waveguide. It demonstrates successful 40 Gb/s-to-10 Gb/s demultiplexing resulting in four error free demultiplexed channels.For further integration of the demultiplexing process, this thesis explores achieving tunable optical delays in silicon waveguides. It shows two approaches for implementing sidewall grating structures, serial Bragg grating arrays and the step-chirped Bragg gratings. Both approaches were fabricated and characterized and demonstrate relatively large delays (up to 65 ps) in discrete steps (from 15 ps to 32 ps) over wide bandwidths (from 35 nm to 70 nm), however they require further optimization. All-optical signal processing and optical devices presented in this thesis provide building blocks and indicate future steps that can lead toward fully integrated OTDM demultiplexer in SOI.L'augmentation incessante de la demande pour de larges bandes passantes crée de grandes tensions sur les technologies de communications existantes. Cela met en évidence le besoin d'améliorer la capacité et l'extensibilité des systèmes de transmission existants et futurs. Cette question peut être résolue, entre autres, par l'exploration des capacités de formats de modulation différents. Cette thèse examine un schéma de (dé)multiplexage optique temporel (OTDM) et présente une plateforme pour la mise en place d'un système pour le traitement de signaux exclusivement optiques sur silicium sur isolant (SOI) qui s'appuie sur le démultiplexage OTDM. Le démultiplexage OTDM et les délais optiques réglables, tous deux implémentés sur des dispositifs en silicium à l'échelle nanométrique, sont démontrés avec succès. Le démultiplexage OTDM est effectuée par l'exploitation de la non-linéarité des guides d'onde sur silicium. Cette technique emploie le phénomène de mélange à quatre ondes (FWM) choisi pour son potentiel pour les très hautes fréquences de données grâce à sa nature instantanée en plus de posséder l'avantage d'être transparent aux formats de modulation. Cette thèse démontre que le démultiplexage OTDM exclusivement optique peut être effectué en deux étapes, la production de ligne à retard ajustable en continue suivit par un procédé de démultiplexage, tous deux implémentés dans le même guide d'onde sur silicium. Un démultiplexage de 40 Gb/s à 10 Gb/s résultant en quatre canaux démultiplexés sans erreur est démontré avec succès. Pour une intégration plus poussée du procédé de démultiplexage, cette thèse examine la possibilité de créer un délai optique ajustable dans les guides d'onde sur silicium. Deux approches pour la mise en œuvre de réseaux sur les parois d'un guide d'onde sont démontrées: une série de réseaux de Bragg et des réseaux de Bragg chirpés. Les deux approches ont été fabriquées et caractérisées et démontrent des délais relativement larges (jusqu'à 65 ps) par étapes discontinues (de 15 ps à 32 ps) sur une bande passante large (de 35 nm à 70 nm). Ces approches doivent cependant être davantage optimisées. Le traitement de signaux exclusivement optique et les dispositifs optiques présentés dans cette thèse fournissent les étapes et les informations nécessaires qui pourraient mener à un démultiplexeur OTDM sur silicium complètement intégré.
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Jackson, Stacey Michael. "Optical characterisation of cubic silicon carbide". Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/842961/.
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The varied properties of Silicon Carbide (SiC) are helping to launch the material into many new applications, particularly in the field of novel semiconductor devices. In this work, the cubic form of SiC is of interest as a basis for developing integrated optical components. Here, the formation of a suitable SiO2 buried cladding layer has been achieved by high dose oxygen ion implantation. This layer is necessary for the optical confinement of propagating light, and hence optical waveguide fabrication. Results have shown that optical propagation losses of the order of 20 dB/cm are obtainable. Much of this loss can be attributed to mode leakage and volume scattering. Mode leakage is a function of the effective oxide thickness, and volume scattering related to the surface layer damage. These parameters have been shown to be controllable and so suggests that further reduction in the waveguide loss is feasible. Analysis of the layer growth mechanism by RBS, XTEM and XPS proves that SiO2 is formed, and that the extent of formation depends on implant dose and temperature. The excess carbon generated is believed to exit the oxide layer by a number of varying mechanisms. The result of this appears to be a number of stable Si-C-O intermediaries that form regions to either depth extreme of the SiO2 layer. Early furnace tests suggest a need to anneal at temperatures approaching the melting point of the silicon substrate, and that the quality of the virgin material is crutial in controlling the resulting oxide growth.
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Fardad, Mohammad Ali. "Fabrication of sol-gel silica-on-silicon waveguides doped with semiconductor quantum dots for integrated optics". Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307565.
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Hobbs, Gareth. "Optical properties of silicon-on-insulator waveguide arrays and cavities". Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636523.
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This thesis details work undertaken over the past three and a half years looking at the optical properties of silicon-on-insulator waveguide arrays and 1D photonic crystal microcavities. Chapter 1 contains relevant background information, while chapters 2, 3 and 4 contain results of experimental work. Chapter 5 summarises the results and conclusions of the preceding chapters and also suggests some directions for possible future research. Chapter 1 starts by introducing some of the fundamental aspects of guided wave optics and how these relate to silicon-on-insulator waveguides. The modes of single,uncoupled silicon waveguides are described, along with a brief description of how such waveguides can be fabricated. Following this a short introduction to optical cavities and the relevant parameters that can be used to describe them is provided. In Chapter 2 results are presented that experimentally confirm the presence of couplinginduced dispersion in an array consisting of two strongly-coupled silicon-on-insulator waveguides. This provides an additional mechanism to tailor dispersion and shows that it is possible to achieve anomalous dispersion at wavelengths where the dispersion of a single wire would be normal. In Chapter 3 the focus switches to the linear properties of 1D photonic crystal microcavities in silicon. The optical transmission of a number of different devices are examined allowing the identification of suitable microcavities for use in nonlinear measurements. Microcavities with Q-factors in excess of ∼40,000 were selected for use in the work presented in Chapter 4, whilst the possibility of thermally tuning the microcavity resonances is also investigated. A cavity resonance shift of 0.0770± 0.0004 nm K-1 is measured experimentally. Chapter 4 looks at the nonlinear transmission of those microcavities identified as suitable in Chapter 3. More specifically, the response of the microcavities to thermal and free carrier induced bistability is considered. Thermally induced bistability is observed at a threshold power of 240 μW for the particular cavity chosen, with a thermal time of 0.6 μs also measured. Free carrier induced bistability is then observed for pulses with nanosecond durations and milliwatt peak powers. Following that, the interplay of thermal and free carrier effects is observed using input pulses of a suitable duration.
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Lai, Qun. "Silica on silicon waveguides with square diffused structure and their components for optical fiber communication /". [S.l.] : [s.n.], 1998. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=12600.
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Yang, Shun-Hui. "Giant birefringence silicon nanophotonic multi-slot waveguides for optical delay line applications". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3329926.
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Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed November 14, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 96-103).
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Naskar, Sudipto. "Deposition and Characterization of silicon oxynitride material for the fabrication of optical waveguides". Case Western Reserve University School of Graduate Studies / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1123163431.
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Hussein, Mohamed Gamar. "Optimization of PECVD boron-phosphorus doped silicon oxynitride for low-loss optical waveguides". Enschede : University of Twente [Host], 2007. http://doc.utwente.nl/57857.
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Lee, Kevin Kidoo 1972. "Transmission and routing of optical signals in on-chip waveguides for silicon microphotonics". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8768.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2001.Includes bibliographical references (p. 139-142).
In this thesis, guiding and routing of optical signals in high index difference ([delta]m) waveguide systems are studied for silicon microphotonic applications. High [delta]n waveguide systems offer compact device sizes that enable highly dense integrated optics suitable for silicon microphotonics. Scattering loss due to the roughness at the core/cladding interfaces is identified as a major source of loss in a high M system. Using both experimental and theoretical approaches, the interdependence of scattering loss, waveguide dimension, and roughness is investigated. We developed a 3 dimensional model that successfully explains the scattering loss dependence on the waveguide dimension. Using this model, a loss contour map is constructed to better understand the scattering loss from interface roughness. This map provides an effective methodology to reduce roughness scattering, which we used to develop two fabrication technologies. Loss reduction from 32 dB/cm to 0.8 dB/cm is achieved for [delta]n =2.0. This is the lowest loss ever achieved for a single-mode, high An system. PolySi/Si02 waveguide systems are investigated due to the compatibility of multi-level processing. Our best PolySi/Si02 waveguide shows additional 10 dB/cm loss, coming mainly from the top surface roughness due to grain boundary grooving. compared to a Si/Si02 waveguide. Compact high An routing devices such as round bends, Y-splitters, and Multi-Mode Interference (MMI) splitters are fabricated and tested. We show that single-mode waveguide bends exhibit μm size bending with low loss and single-mode splitters show splitting with good uniformity. MMis show advantages over equivalent Y-splitter based structures in terms of size and loss. Our MMI design led to the fabrication of the smallest optical 1x16 fanout ever built. High Transmission Cavity (HTC) based bends, splitters, and resonators, that are compatible with an anisotropic etching technique, are demonstrated. An index engineering map, which shows competing trends of minimum bending radius and scattering loss as tin is changed. is constructed. From this map, the optimal M can be found for a given fabrication technology. Improvement in the fabrication technology allows for higher tin and provides a scaling law in optical devices. This point is proven by our 0.8 dB/cm Si/Si02 waveguides, which lifts the upper limit of the usable [delta]n.
by Kevin Kidoo Lee.
Ph.D.
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Bhatnagar, Sameer. "Fabrication of a vertically stacked grating coupler for optical waveguides in silicon-on-insulator". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116025.
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Couplers that can couple light vertically between stacked waveguides are finding importance in the push towards higher density and lower cost optoelectronics. A compact grating coupler (12.8mum) designed by a former student is implemented in this project. The device is patterned by reactive-ion-etch into silicon-on-insulator with a 250 nm thick device layer, ensuring single mode operation. Alignment marks are patterned into the backside so that aligned bonding can be carried out. A die bonding recipe is developed using an intermediate adhesive film of SU-8-2. A novel approach to creating optically smooth input facets is included in the final steps of the process. Optical testing remains to be done.
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Wismayer, A. C. "Characterisation of stripe optical waveguides fabricated by silicon impurity induced disordering of GaAs/AlGaAs MQW material". Thesis, University of Surrey, 1991. http://epubs.surrey.ac.uk/843125/.
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Impurity Induced Layer Disordering (IILD) of a GaAs/AlGaAs Multi Quantum Well (MQW) structure is known to produce a change in the refractive index dependent on the polarisation of the propagating mode. This index change can be used to provide lateral confinement in stripe optical waveguides, which are an essential component in any integrated optical circuit. Silicon implantation has been used to disorder GaAs/AlGaAs MQWs and the effects of implantation dose, encapsulant and annealing conditions on the disordering process have been investigated using Photoluminescence (PL). It was observed that deep level emissions accompanied the disordering and the results suggest that the degree of intermixing and the deep level emissions were determined by several competing processes. Calculation of the deep level/band-edge integrated intensity ratio for these emissions, provided an indication of the suitability of the process for the fabrication of disorder delineated stripe waveguides, where a correlation between the propagation loss of the waveguides and the integrated intensity ratio was observed. Buried stripe optical waveguides fabricated using Si+ IILD has been demonstrated for the first time in this work. Waveguide assessment using end-fire coupling was performed with the propagation losses and modal dimensions determined. The lowest loss of a waveguide fabricated by IILD presented in this thesis is 21.9dBcm-1 and it is suggested that the deep level states observed using PL are a significant source of attenuation of the propagating mode in the side walls of the waveguides.
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Khan, Saeed. "Silicon photonic devices for optical delay lines and mid infrared applications". Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5961.
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Silicon photonics has been a rapidly growing subfield of integrated optics and optoelectronic in the last decade and is currently considered a mature technology. The main thrust behind the growth is its compatibility with the mature and low-cost microelectronic integrated circuits fabrication process. In recent years, several active and passive photonic devices and circuits have been demonstrated on silicon.
Optical delay lines are among important silicon photonic devices, which are essential for a variety of photonic system applications including optical beam-forming for controlling phased-array antennas, optical communication and networking systems and optical coherence tomography. In this thesis, several types of delay lines based on apodized grating waveguides are proposed and demonstrated. Simulation and experimental results suggest that these novel devices can provide high optical delay and tunability at very high bit rate.
While most of silicon photonics research has focused in the near-infrared wavelengths, extending the operating wavelength range of the technology into in the 3–5 &"181;m, or the mid-wave infrared regime, is a more recent field of research. A key challenge has been that the standard silicon-on-insulator waveguides are not suitable for the mid-infrared, since the material loss of the buried oxide layer becomes substantially high. Here, the silicon-on-sapphire waveguide technology, which can extend silicon's operating wavelength range up to 4.4 &"181;m, is investigated. Furthermore, silicon-on-nitride waveguides, boasting a wide transparent range of 1.2–6.7 ?m, are demonstrated and characterized for the first time at both mid-infrared (3.39 ?m) and near-infrared (1.55 ?m) wavelengths.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Namnabat, Soha, i Soha Namnabat. "Novel Optical Materials for Passive Photonic Applications". Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/623168.
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Advances in photonic materials are critical to the progress of photonic devices and optical systems. Even though a variety of materials, e.g. semiconductors, oxide based glasses, and polymers exist which are being used for numerous applications, there is a growing need to develop and find new materials in order to push the limits we are bound by with conventional materials, in pursuit of higher performance, higher levels of integration and lower cost. In this realm, new material development has had a considerable impact, as it is the material properties (optical, thermal, mechanical, electrical, ...) in addition to their processing and compatibilities with standard processes that enable us the creation of entirely new devices or improve the performance of currently available optical devices. In this dissertation, I will demonstrate the application of two new materials for novel photonic components. In the first part of the dissertation, I discuss how a hybrid approach to the silicon photonics platform can reduce thermal sensitivity using sol-gel based inorganic-organic hybrid materials. The approach is to design the optical waveguide so that it maintains its performance in a passive manner in response to environmental temperature variations and, thus, does not need external temperature control resulting in reduced electrical power consumption. Sol-gel materials are well-known, but they haven’t been exploited like polymers and titanium dioxide to be cladding layers to enable athermal silicon waveguides. In this work I show their advantages with respect to previous materials that were employed for athermal microring resonators. I studied the thermal curing parameters of the sol-gel and its effect on thermal wavelength shift of the microring resonance. With this method, I was able to achieve a thermal shift down to -6.8 pm/°C for transverse electric (TE) polarization, as well as thermal shifts below 1 pm/°C for transverse magnetic (TM) polarization in the C band under different curing conditions, all while preserving high Q resonator performance. The results and methodology described opens a new and more manufacturable approach to attain athermal silicon photonic devices. In the second part of the dissertation, I introduced a new, sulfur rich, low cost copolymer material developed by our colleagues in the chemistry department. This copolymer has unique properties that conventional optical polymers, such as polymethylmethacrylate and polycarbonate, lack, while also having low cost. I demonstrated that these polymers have very good processing capabilities, being easily moldable to make free space optical elements and solution processable for use in integrated optics. I studied their linear and nonlinear optical properties, finding them to possess high refractive indices and transparencies over a wide range from 550 nm to 6 µm, except for a small region of absorption from 3-3.3 µm. Finally, I demonstrated that these new copolymers are suitable and economical alternative for shortwave and midwave infrared optics (SWIR and MWIR, respectively).
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Chen, Li. "Hybrid Silicon and Lithium Niobate Integrated Photonics". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429660021.
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You, Jie. "Calculation of bit error rates of optical signal transmission in nano-scale silicon photonic waveguides". Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1565186/.
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In this dissertation, a comprehensive and rigorous analysis of BER performance in the single- and multi-channel silicon optical interconnects is presented. The illustrated computational algorithms and new results can furnish one with insight of how to engineer waveguide dimensions, optical nonlinearity and dispersion, in order to facilitate the design and construction of the ultra-fast and low-cost chip-level communications for next-generation high-performance computing systems. Two types of optical links have been intensively discussed in this dissertation, namely a strip single-mode silicon photonic waveguide and a silicon photonic crystal waveguide. Different types of optical input signals are considered here, including an ON-OFF keying modulated nonreturn-to-zero continuous-wave signal, a phase-shift keying modulated continuous-wave signal, and a Gaussian pulsed signal, all in presence of white noise. The output signal is detected and analyzed using direct-detection optical receivers. To model the signal propagation in the single- and multi-channel silicon photonic waveguides, we employ both rigorous theoretical models that incorporate all relevant linear and nonlinear optical effects and the mutual interaction between the free carriers and the optical field, as well as their linearized version valid in the low-noise power regime. Particularly, the second propagation model is designed only for optical continuous-wave signals. Equally important, the bit error rate (BER) of the transmitted signal is accurately and efficiently calculated by using the Karhunen-Loeve series expansion methods, with these approaches performed via the time-domain, frequency-domain, and Fourier-series expansion, separately. Based on the theoretical models proposed in this work, a system analysis engine has been constructed numerically. This engine can not only analyze the underlying physics of silicon waveguides, but also evaluate the system performance, which is extremely valuable for the configuration and optimization of the optical networks on chip.
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Killge, S., S. Charania, K. Richter, N. Neumann, Z. Al-Husseini, D. Plettemeier i J. W. Bartha. "Realization of optical multimode TSV waveguides for Si-Interposer in 3D-chip-stacks". SPIE, 2017. https://tud.qucosa.de/id/qucosa%3A35138.
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Optical connectivity has the potential to outperform copper-based TSVs in terms of bandwidth at the cost of more complexity due to the required electro-optical and opto-electrical conversion. The continuously increasing demand for higher bandwidth pushes the breakeven point for a profitable operation to shorter distances. To integrate an optical communication network in a 3D-chip-stack optical through-silicon vertical VIAs (TSV) are required. While the necessary effort for the electrical/optical and vice versa conversion makes it hard to envision an on-chip optical interconnect, a chip-to-chip optical link appears practicable. In general, the interposer offers the potential advantage to realize electro-optical transceivers on affordable expense by specific, but not necessarily CMOS technology. We investigated the realization and characterization of optical interconnects as a polymer based waveguide in high aspect ratio (HAR) TSVs proved on waferlevel.
To guide the optical field inside a TSV as optical-waveguide or fiber, its core has to have a higher refractive index than the surrounding material. Comparing different material / technology options it turned out that thermal grown silicon dioxide (SiO2) is a perfect candidate for the cladding (nSiO2 = 1.4525 at 850 nm). In combination with SiO2 as the adjacent polymer layer, the negative resist SU-8 is very well suited as waveguide material (nSU-8 = 1.56) for the core. Here, we present the fabrication of an optical polymer based multimode waveguide in TSVs proved on waferlevel using SU-8 as core and SiO2 as cladding. The process resulted in a defect-free filling of waveguide TSVs with SU-8 core and SiO2 cladding up to aspect ratio (AR) 20:1 and losses less than 3 dB.
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Schelew, Ellen N. "Nonlinear optical response of triple-mode silicon photonic crystal microcavities coupled to single channel input and output waveguides". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63353.
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Optical and opto-electronic components play important roles in both classical and quantum information processing technologies. Despite fundamental differences in these technologies, both stand to benefit greatly from moving away from bulky, individually packaged components, toward a scalable platform that supports dense integration of low power consumption devices. Planar photonic circuits, composed of devices etched in a thin slab of high refractive index material, are considered an excellent candidate, and have been used to realize many key components, including low-loss waveguides, light sources, detectors, modulators, and spectral filters. In this dissertation, a novel triple-microcavity structure was designed, externally fabricated, and its linear and nonlinear optical properties were thoroughly characterized. The best of the structures exhibited both high four-wave mixing conversion efficiencies and low threshold optical bistability, which are relevant to frequency conversion and all-optical switching applications.
The device consisted of three coupled photonic crystal (PC) microcavities with three nearly equally spaced resonant frequencies near telecommunication wavelengths (λ ~ 1.5 μm), with high quality factors (~ 10⁵, 10⁴ and 10³). The microcavity system was coupled to independent input and output PC waveguides, and the cavity-waveguide coupling strengths were engineered to maximize the coupling of the input waveguide to the central mode, and the output waveguide to the two modes on either side.
A novel and sophisticated measurement and analysis protocol was developed to characterize the devices. This involved measuring and modelling the linear and nonlinear transmission characteristics of each of the modes separately with a single tunable laser, as well as the frequency conversion efficiency (via stimulated four-wave mixing) when two tunable lasers pumped two of the modes, and the power generated in the third mode was monitored.
Comparisons of the entire set of model and experimental results led to the conclusion that this structure can be used to achieve both low-power-threshold optical switching and high efficiency four-wave-mixing-based frequency conversion. The advantages of this structure over others in the literature are its small footprint, multi-mode functionality and independent input and output channels. The main disadvantage that requires further refinement, has to do with its sensitivity to fabrication imperfections.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Ben, Masaud Taha. "Development of low temperature fabrication processes of n-ZnO/p-Si optical switch and poly-silicon waveguides for CMOS-compatible multi-layered silicon photonics". Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/370612/.
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The potential advantages and applications of Silicon Photonics (SiP) has initiated substantial research efforts. Silicon photonics has been favourably nominated to replace the current copper interconnects due to their high bandwidth, small footprint, and potentially low power consumption. However, the majority of the research into silicon photonics has been based on the silicon-on insulator (SOI) platform. The focus on the SOI platform has limited the design of silicon photonic devices to two-dimensional (2D) structures. Moreover, the fabrication of optical active devices based on silicon photonics has relied on high temperature processing that is not compatible with CMOS back-end integration. New materials that are depositable at low temperatures can offer new possibilities for multi-layered, CMOS back-end compatible, and low optical loss silicon photonic devices. In this project, zinc oxide (ZnO) was investigated as a potential low temperature material whose fabrication is compatible with CMOS technology. Specifically, the naturally n-type doped ZnO can potentially form a heterojunction with p-type silicon without the need for high temperature processing. Poly-silicon is also a depositable and CMOS compatible material that can potentially form future multi-layered silicon photonic structures. However, low optical loss in poly-silicon has been based on high-temperature processing to improve the crystallinity and roughness of the deposited material. The deposition of poly-silicon in the SiP technology have been mainly carried out using plasma-enhanced chemical vapour deposition (PECVD) and other deposition techniques remain under investigated. In this project, ZnO was, for the first time, deposited at low-temperature (150 ˚C) using atomic layer deposition (ALD) on a silicon waveguide to form a heterojunction diode capable of producing optical switching in the silicon core. Optical switching in the n-ZnO/p-Si heterojunction was caused by the plasma dispersion effect. The design of the optical switch comprised a straight silicon waveguide (width = 1000 nm, height = 220 nm, slabheight = 60 nm) partially covered with a thin ZnO film (thickness = 10 nm). The commonly used highly doped p+ region were not included in the devices because of the high thermal budget (T ' 900 ˚C) needed to activate the dopant. Moreover, the aluminium (Al) metal contacts were not annealed because the annealing temperature (Ts = 425˚C) exceeds the high-temperature threshold (Ts = 400˚C). An extinction ratio of ~ 10 dB was achieved for a 1 mm long device at 20 V forward-bias. This result can be expressed as a figure of merit of 5 dB/cm.V. The insertion loss of the device was estimated to be ~ 1:2 dB. The maximum switching speed of the devices was found to be ~1 MHz. Al-though this performance is inferior to the state-of-the-art silicon optical switches, it offers the first silicon-based electro-optical switch fabricated at low-temperatures with low insertion loss. Detailed analysis of the I-V and switching characteristics of the device revealed large series resistance and capacitance. It was also found that the switching speed is primarily governed by the RC time constant of the device rather than the minority carrier lifetime. This fact has led us to believe that the device functions as both injection and accumulation electro-absorption switch. A thin SiO2 layer is suspected to form at the ZnO/Si interface that facilitates the accumulation operation of the device and increases the RC time constant. The first low loss and low-temperature poly-silicon waveguides are demonstrated in this project. Hot-wire chemical vapour deposition (HWCVD) was used to deposit poly-silicon films at 240˚C. The propagation loss of the TE mode for a 600 by 220 nm waveguide was 13:5 dB/cm. Detailed simulation analysis revealed that at least 60% of the loss was caused by the roughness of the top surface of the waveguides. The RMS roughness was measured using atomic force microscopy (AFM) and was found to be 8:9 nm. Optimisation of the design, the deposition process, and the reduction of the top surface roughness, through surface planarisation, led to a reduction in the propagation loss of the TE mode to ~8:5 dB/cm while still maintaining low deposition temperature of 360˚C. The crystal volume fraction of the optimised poly-silicon film was found to be ~96%. An electro-optical switch based on ZnO and poly-silicon heterojunction was fabricated on a multi-layered poly silicon structure. However, there were problems with the metal contact pads as well as the thickness of the first poly-silicon layer. Future work will focus on improving the n-ZnO/p-Si heterojunction electro-optical performance by adapting an accumulation type structure as well as optimising the multi-layered poly-silicon platform.
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Floether, Frederik. "Development of SiOxNy waveguides for integrated quantum photonics". Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/253107.
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The development of integrated quantum photonics is integral to many areas of quantum information science, in particular linear optical quantum computing. In this context, a diversity of physical systems is being explored and thus versatility and adaptability are important prerequisites for any candidate platform. Silicon oxynitride is a promising material because its refractive index can be varied over a wide range. This dissertation describes the development of silicon oxynitride waveguides for applications in the field of integrated quantum photonics. The project consisted of three stages: design, characterisation, and application. First, the parameter space was studied through simulations. The structures were optimised to achieve low-loss devices with a small footprint at a wavelength of 900 nm. Buried channel waveguides with a cross-section of 1.6 ?m x 1.6 ?m and a core (cladding) refractive index of 1.545 (1.505) were chosen. Second, following their fabrication with plasma-enhanced chemical vapour deposition, electron beam lithography, and reactive ion etching, the waveguides were characterised. The refractive index was shown to be tunable from the silica to the silicon nitride regime. Optimised tapers significantly improved the coupling efficiency. The minimum bend radius was measured to be less than 2 mm. Propagation losses as low as 1.45 dB cm-1 were achieved. Directional couplers with coupling ratios ranging from 0 to 1 were realised. Third, building blocks for linear optical quantum computing were demonstrated. Reconfigurable quantum circuits consisting of Mach-Zehnder interferometers with near perfect visibilities were fabricated along with a four-port switch. The potential of quantum speedup was illustrated by carrying out the Deutsch-Jozsa algorithm with a fidelity of 100 % using on-demand single photons from a quantum dot. This dissertation presents the first implementation of tunable Mach-Zehnder interferometers, which act on single photons, based on silicon oxynitride waveguides. Furthermore, for the first time silicon oxynitride photonic quantum circuits were operated with on-demand single photons. Accordingly, this work has created a platform for the development of integrated quantum photonics.
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LoStracco, Gregory 1960. "Furance and carbon dioxide laser densification of sol-gel derived silicon oxide-titanium oxide-aluminum oxide planar optical waveguides". Thesis, The University of Arizona, 1994. http://hdl.handle.net/10150/291388.
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An experimental investigation on the furnace and CO₂ laser densification of sol-gel derived SiO₂-TiO₂-Al₂O₃ planar optical waveguides was performed. Solutions containing equal mole fractions of tetraethoxysiline [Si(C₂H₅O)₄], titanium ethoxide [Ti(C₂H₅O)₄], aluminum tri-sec-butoxide [Al(C₄H₉O)₃] were used to spin films with a nominal 2:2:1 molar SiO₂-TiO₂-Al₂O₃ composition. Emphasis was placed on determining what effects the densification techniques had on film shrinkage, index change, crystallization and composition. Film shrinkage and refractive index change were found to be similar for both densification techniques. Fully dense, amorphous film were obtained with both methods. After densification, further heating caused titania crystalline phases to form with both processing techniques. However, anatase formed in the furnace fired films while rutile formed in the laser irradiated films.
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Tegegne, Zerihun. "SiGe/Si Microwave Photonic devices and Interconnects towards Silicon-based full Optical Links". Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1070/document.
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Avec la croissance forte de ces dernières années des objets connectés les technologies de communication optique et radio voient davantage d’opportunités de s’associer et se combiner dans des technologies bas-couts Photoniques-Microondes (MWP). Les réseaux domestiques en sont un exemple. La bande millimétrique notamment, de 57GHz à 67GHz, est utilisé pour contenir les exigences des communications sans fils très haut-débit, néanmoins, la couverture de ces systèmes wireless est limitée en intérieur (indoor) essentiellement à une seule pièce, à la fois du fait de l’atténuation forte de l’atmosphère dans cette bande de fréquence, mais aussi de fait de l’absorption et de la réflexion des murs. Ainsi il nécessaire de déployer une infrastructure pour diffuser l’information au travers d’un système d’antennes distribuées. Les technologiques optiques et photoniques-microondes sont une des solutions envisagées. Les technologies MWP se sont également étendues et couvrent une gamme très large d’applications incluant les communications mobiles 5G, les analyses biomédicales, les communications courtes-distances (datacom), le traitement de signal par voie optique et les interconnexions dans les véhicules et aéronefs. Beaucoup de ces applications requièrent de la rapidité, de la bande-passante et une grande dynamique à la fois, en même temps de demander des dispositifs compacts, légers et à faible consommation. Le cout d’implémentation est de plus un critère essentiel à leur déploiement, en particulier dans l’environnement domestique ainsi que dans d’autres applications variées des technologies MWP.Ce travail de thèse vise ainsi le développement de composants photonique-microondes (MPW) intégrés en technologie BiCMOS ou Bipolaire SiGe/Si, à très bas coût, incluant les phototransistors bipolaires à hétérojonctions (HPT) SiGe/Si, les Diodes Electro-Luminescentes (LED) Si et SiGe, ainsi que l’intégration combinées des composants optoélectroniques et microondes, pour l’ensemble des applications impliquant des courtes longueurs d’ondes (de 750nm à 950nm typiquement).Ces travaux se concentrent ainsi sur les points suivants :La meilleure compréhension de phototransistors SiGe/Si latéraux et verticaux conçus dans une technologie HBT SiGe 80GHz de Telefunken GmbH. Nous traçons des conclusions sur les performances optimales du phototransistor. Les effets de photodétection du substrat et de la dispersion spatiale des flux de porteurs sont analysés expérimentalement. Cette étude aide à développer des règles de dessin pour améliorer les performances fréquentielles du phototransistor HPT pour les applications visées.Dans l’objectif de développer de futures interconnexions intra- et inter- puces, nous concevons des lignes de transmissions faibles-pertes et des guides d’ondes optiques polymères sur Silicium faible résistivité. Il s’agit d’une étape afin d’envisager des plateformes Silicium dans lesquelles les HPT SiGe pourront potentiellement être intégrés de manière performante à très bas coût avec d’autres structures telles que des lasers à émission par la surface (VCSEL), afin de construire un transpondeur optique complet sur une interface Silicium. Le polymère est utilisé comme une interface diélectrique entre les lignes de transmission et le substrat, pour les interconnexions électriques, et pour définir le gain du guide d’onde optique dans les interconnexions optiques.La conception, la fabrication et la caractérisation du premier lien photonique-microonde sur puce Silicium sont menées en se basant sur la même technologie HBT SiGe 80GHz de Telefunken dans la gamme de longueur d’onde 0,65µm-0,85µm. Ce lien optique complétement intégré combine des LEDS Silicium en régime d’avalanche (Si Av LED), des guides d’ondes optiques Nitrure et Silice ainsi qu’un phototransistor SiGe. Un tel dispositif pourrait permettre d’accueillir à l’avenir des communications sur-puce, de systèmes micro-fluidiques et des applications d’analyse biochimiquesWith the recent explosive growth of connected objects, for example in Home Area Networks, the wireless and optical communication technologies see more opportunity to merge with low cost MicroWave Photonic (MWP) technologies. Millimeter frequency band from 57GHz to 67GHz is used to accommodate the very high speed wireless data communication requirements. However, the coverage distance of these wireless systems is limited to few meters (10m). The propagation is then limiting to a single room mostly, due to both the high propagation attenuation of signals in this frequency range and to the wall absorption and reflections. Therefore, an infrastructure is needed to lead the signal to the distributed antennas configuration through MWP technology. Moreover, MWP technology has recently extended to address a considerable number of novel applications including 5G mobile communication, biomedical analysis, Datacom, optical signal processing and for interconnection in vehicles and airplanes. Many of these application areas also demand high speed, bandwidth and dynamic range at the same time they require devices that are small, light and low power consuming. Furthermore, implementation cost is a key consideration for the deployment of such MWP systems in home environment and various integrated MWP application.This PhD deals with very cheap, Bipolar or BiCMOS integrated SiGe/Si MWP devices such as SiGe HPTs, Si LEDs and SiGe LEDs, and focused on the combined integration of mm wave and optoelectronic devices for various applications involving short wavelength links (750nm to 950nm).This research focused on the study of the following points:The better understanding of vertical and lateral illuminated SiGe phototransistors designed in a 80 GHz Telefunken GmbH SiGe HBT technology. We draw conclusions on the optimal performances of the phototransistor. The light sensitive Si substrate and two-dimensional carrier flow effects on SiGe phototransistor performance are investigated. This study helps to derive design rules to improve frequency behavior of the HPT for the targeted applications.For future intra /inter chip hybrid interconnections, we design polymer based low loss microwave transmission lines and optical waveguides on low resistive silicon substrate. It is a step to envisage further Silicon based platforms where SiGe HPT could be integrated at ultra-low cost and high performances with other structures such high-speed VCSEL to build up a complete optical transceiver on a Silicon optical interposer. The polymer is used as dielectric interface between the line and the substrate for electrical interconnections and to design the core and cladding of the optical waveguide.The design, fabrication and characterization of the first on-chip microwave photonic links at mid infrared wavelength (0.65-0.85μm) based on 80 GHz Telefunken GmbH SiGe HBT technological processes. The full optical link combines Silicon Avalanche based Light Emitting Devices (Si Av LEDs), silicon nitride based waveguides and SiGe HPT. Such device could permit hosting microfluidic systems, on chip data communication and bio-chemical analysis applications
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Marinins, Aleksandrs. "Polymer Components for Photonic Integrated Circuits". Doctoral thesis, KTH, Skolan för teknikvetenskap (SCI), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-219556.
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Optical polymers are a subject of research and industry implementation for many decades. Optical polymers are inexpensive, easy to process and flexible enough to meet a broad range of application-specific requirements. These advantages allow a development of cost-efficient polymer photonic integrated circuits for on-chip optical communications. However, low refractive index contrast between core and cladding limits light confinement in a core and, consequently, integrated polymer device miniaturization. Also, polymers lack active functionality like light emission, amplification, modulation, etc. In this work, we improved a performance of integrated polymer waveguides and demonstrated active waveguide devices. Also, we present novel Si QD/polymer optical materials. In the integrated device part, we demonstrate optical waveguides with enhanced performance. Decreased radiation losses in air-suspended curved waveguides allow low-loss bending with radii of only 15 µm, which is far better than >100 µm for typical polymer waveguides. Another study shows a positive effect of thermal treatment on acrylate waveguides. By heating higher than polymer glass transition temperature, surface roughness is reflown, minimizing scattering losses. This treatment method enhances microring resonator Q factor more than 2 times. We also fabricated and evaluated all-optical intensity modulator based on PMMA waveguides doped with Si QDs. We developed novel hybrid optical materials. Si QDs are encapsulated into PMMA and OSTE polymers. Obtained materials show stable photoluminescence with high quantum yield. We achieved the highest up to date ~65% QY for solid-state Si QD composites. Demonstrated materials are a step towards Si light sources and active devices. Integrated devices and materials presented in this work enhance the performance and expand functionality of polymer PICs. The components described here can also serve as building blocks for on-chip sensing applications, microfluidics, etc.QC 20171207
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Horikawa, Tsuyoshi. "A study of advanced integrated semiconductor device and process technologies for data storage and transmission". 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215222.
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STENGER, VINCENT EDWARD. "VERTICAL MULTIMODE INTERFERENCE OPTICAL WAVEGUIDE TAPS FOR SILICON CMOS CIRCUITS". University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1069795415.
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Harvey, Eric J. "Design and fabrication of silicon on insulator optical waveguide devices /". Online version of thesis, 2006. https://ritdml.rit.edu/dspace/handle/1850/2597.
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Metcalf, Benjamin James. "Silica-on-silicon waveguide circuits and superconducting detectors for integrated quantum information processing". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:8b5482f6-93a7-4d6e-b335-ba258ad3de1e.
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Building complex quantum systems has the potential to reveal phenomena that cannot be studied using classical simulation. Photonics has proven to be an effective test-bed for the investigation of such quantum-enhanced technologies, however, the proliferation of bulk optical components is unlikely to be a scalable route towards building more complex devices. Instead, the miniaturisation, inherent phase stability and trivial alignment afforded by integrated photonic systems has been shown to be a promising alternative. In the first half of this thesis, we describe experiments exploiting the quantum interference of three single photons on a reconfigurable integrated photonic chip. We develop a low-loss source of single photons and introduce a low-loss silica-on-silicon waveguide architecture which enables us to show the first genuine quantum interference of three single photons on an integrated platform. A loss-tolerant, element-wise characterisation scheme is developed along with a statistical test to verify that this multi-photon circuit behaves as expected. We then make use of this three-photon interference to detail the first proof-of-principle demonstration of a new intermediate model of quantum computation called boson sampling. Finally, we perform an on-chip demonstration of the quantum teleportation protocol where all key parts --- entanglement preparation, Bell-state analysis and quantum state tomography --- are performed on a reconfigurable photonic chip. The element-wise characterisation scheme developed earlier is shown to be critical to mitigate fabricated component errors. We develop a theoretical model to account for all sources of possible error in the circuit and find good agreement with the measured teleported state fidelities, which exceed the average teleportation fidelity possible with a classical device. We identify the elements of this error budget relevant to scaling and propose improvements to chip characterisation and fabrication in order to achieve high fidelity operation. In the second half, we discuss the use of high efficiency superconducting transition edge sensors in enabling quantum experiments using more photons. We detail the installation and characterisation of these detectors in a new lab in Oxford. We achieve good photon number-resolution and high-efficiency operation. Work to integrate these detectors on the silica-on-silicon waveguide architecture is discussed and we detail the optical and thermal device modelling performed to optimise the on-chip detection efficiency. New, on-chip detectors, fabricated according to this design are shown to operate as expected and achieve high-efficiency and good energy resolution.
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Roncone, Ronald Louis. "An experimental and theoretical investigation of waveguide scatter, with applications to solution-deposited silica-titania planar waveguides". Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/186042.
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A theoretical and experimental investigation of scatter from surface roughness and core refractive index fluctuations in planar waveguides was performed, with an emphasis placed on applications in solution-deposited SiO₂-TiO₂ (silica titania) planar waveguiding systems. A perturbation theory was used to model TE₀ mode scattering from surface and volume microstructure, and to predict attenuation when provided with the necessary waveguide and scattering parameters. Final forms for the equations predicting surface and volume scatter losses into the cover and substrate regions of the waveguides were provided. The rather complex perturbation theory model of surface scatter was compared to a very simple, intuitive model based on the Rayleigh criterion. The two models were shown to predict surface induced attenuation values which were in very close agreement when the guided mode propagation angle approached 90°. Thus, the simple model was shown to be adequate for predicting TE₀ mode surface scattering losses for waveguides which were very thick, and/or possessed a low refractive index. Considerable emphasis was placed on providing a simple, physical picture of guided mode scattering, utilizing rays to represent the scattered light. Following the development of this technique, it was utilized to explain the origins of interference peaks in surface scattered radiation at certain values of film thickness. Solution chemistry and processing methodologies for 50:50 mol% and 35:65 mol% SiO₂-TiO₂ sol-gel films, yielding high quality, amorphous, glass waveguides, were discussed. Attenuation in the 50:50 mol% films was 1-2 dB/cm, while attenuation in the 35:65 mol% films was 0.3-0.5 dB/cm, at λ = 0.6328 μm. Absorption in these films was negligible. Waveguide losses were measured by transferring the scattered streak to a remote image plane (using a coherent fiber bundle) and scanning it using an automated, stepper-motor controlled, apertured photomultiplier tube. Testing and calibration techniques were described in detail. We found that surface-induced scattering was the dominant loss mechanism in the 35:65 mol% SiO₂-TiO₂ films. Surface roughnesses of the sol-gel films, measured using Atomic Force Microscopy, ranged from about 2-5 A rms, with correlation lengths from about 0.05-0.75 μm.
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Nascimento, Júnior Adriano Ricardo 1991. "Fabricação de microrressonadores ópticos com alto fator de qualidade utilizando nitreto de silício depositado à temperatura ambiente para aplicações em óptica não linear". [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259411.
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Orientadores: Leandro Tiago Manera, Arismar Cerqueira Sodré JúniorDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Neste trabalho foram fabricados microrressonadores em anel com alto fator de qualidade utilizando filmes de nitreto de silício (SixNy) depositados a baixa temperatura (20 °C) utilizando a técnica de deposição ECR-CVD (Deposição em Fase Vapor por Resonância Ciclotrônica do Elétron). Graças à alta não linearidade do SixNy, tais filmes têm sido recentemente usados para aplicações em óptica não linear como a geração de pentes de frequência na banda C de telecomunicações. Para tais aplicações, o guia de onda do dispositivo deve possuir um ponto de dispersão nula no centro da banda C, necessitando de uma grande área. Infelizmente, filmes espessos de nitreto de silício (>400 nm) possuem um alto stress responsável pela ocorrência de rachaduras catastróficas no filme que reduzem drasticamente a eficiência do dispositivo. Utilizando simulações numéricas, demonstrou-se que para valores de índice de refração (n) maiores que 2, a área do guia de onda com zero dispersão em ? = 1,55 ?m é consideravelmente reduzida, necessitando assim de uma menor espessura de filme. Foi obtido um filme de SixNy rico em Si, com índice de refração igual a 2, alta taxa de deposição, baixa concentração de hidrogênio e uma rugosidade média de somente 0,52 nm (4,2 nm de desvio padrão). Devido à baixa temperatura da técnica de deposição empregada, não foi observado traços de stress no filme, permitindo a obtenção de uma espessura de 730 nm utilizando uma única etapa de deposição. Os microrressonadores ópticos fabricados com raios de 60 e 120 ?m apresentaram um FSR (Free Spectral Range) equidistante em toda a banda C e um fator de qualidade de 7,2x10^3 foi obtido experimentalmente. Tais resultados demonstraram a alta eficiência dos dispositivos fabricados com o filme de SixNy desenvolvido e sua promissora aplicação para óptica não linear na banda C de telecomunicações
Abstract: Silicon nitride (SixNy) films deposited by low-pressure electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-CVD) at room temperature are proposed for fabrication of microring resonators with high Q-factor. Due to the high silicon nitride nonlinearity, these films recently have also been used for nonlinear optics applications in the telecommunications C-band. For nonlinear applications such as the generation of frequency combs, the waveguide needs a zero dispersion point in the middle of C-band, requesting large waveguide area. Unfortunately, these thick SixNy films (>400 nm) have high stress and suffer from catastrophic cracking, which reduces the device efficiency. Using numerical simulations it was demonstrated that for refractive index (n) values greater than 2, the area of the waveguide with zero dispersion point at ? = 1.55 ?m is greatly reduced. A Si-rich silicon nitride layer with refractive index of 2, high deposition rate, low hydrogen concentration and roughness average of 0.52 nm with standard deviation of 4.2 nm was obtained. Due to the low temperature deposition, no thermal stress was observed in the SixNy film, allowing a thickness of 730 nm obtained with only one deposition step. After experimental measurements, microring resonators having a radius of 60 and 120 ?m, presented an equidistant Free Spectral Range and a Q-factor of 7.2x10^3 was achieved, showing the high efficiency of the device and their promising application in nonlinear effects in the telecommunication C-band
Mestrado
Eletrônica, Microeletrônica e Optoeletrônica
Mestre em Engenharia Elétrica
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Lanker, Michael. "Arrayed waveguide gratings in indium phosphide using buried waveguides and optical space switches with high on-off ratio in silica /". Zürich, 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13602.
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Maxwell, Graeme D. "Optical waveguide fabrication in silica using flame hydrolysis". Thesis, University of Glasgow, 1990. http://theses.gla.ac.uk/5637/.
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This thesis is concerned with the fabrication, assessment and application of doped silica waveguides using Flame Hydrolysis Deposition. Deposition apparatus has been designed and constructed. This equipment consists of a gas supply assembly, a bubbler cabinet, a deposition box and a chemical scrubber. An optimum sintering regime for the low density silica soot has been established consisting of 60 minutes at 1250oC. This regime is dependent on the levels of P2O5, GeO2 and/or TiO2 doping in the silica host. Independent control of layer thickness and index is achieved. Refractive index can be varied by changing the doping levels, and thickness, by increasing the number of traversals of the hydrolysing flame. Film homogeneity in terms of layer thickness was found to be difficult to control and up to 30% variation in thickness was obtained in some samples. Thermophoretic effects were shown to play an important part in the deposition process. Titanium and phosphorus doped films were found to suffer film degradation and aging. This led to the formation of titanium rich crystals and crystal agglomerates which produced Rayleigh/ Mie scatter in the sintered films. No such problem was found with Germanium, and all films were subsequently fabricated using Germanium and Phosphorus. No out-of-plane scatter was observed in the sintered films. Ridge waveguides were fabricated using lithography and Reactive Ion Etching in a CHF3 plasma, giving waveguides with smooth side walls. Loss assessment was carried out using two techniques, both of which were non-destructive. One involved a video camera to scan across the waveguide and detect the out-of-plane scatter. This technique was sensitive to scattering centres and was less accurate for short lengths of guide. Loss figure varied from 0.2 to over 5 dB/cm depending on the scan length. The second technique involved turning the waveguide into a Fabry-Perot resonator, by coating the end faces of the waveguide. Temperature induced cycles in the output intensity could be used to obtain the waveguide attenuation. This technique was sensitive to the facet angles of the guides which could contribute significantly to the loss measured. Such resonances were obtained in only one sample and gave a loss figure of over 9 dB/cm which is considered unreliable. Films were doped with both Nd3+ and Er3+ using a solution doping technique and fluorescence spectra were obtained for both. Increased scatter was observed in the planar films with such doping. Holographic gratings were fabricated on planar waveguides with a view to their incorporation as feedback elements in a laser structure. Second Harmonic Generation was observed for the first time in planar rib waveguide structures doped with Phosphorus and Germanium. In a `seeding' experiment where 1064nm radiation was launched at the same time as a second harmonic `seed', a two-hundred fold increase was observed in generated second harmonic signal over the background level.
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Hoang, Thi Hong Cam. "Planar slot photonic crystal cavities for on-chip hybrid integration". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS063/document.
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Cette thèse est une contribution à la modélisation et à l'étude expérimentale de cavités à cristaux photoniques à fente développées en vue d’un intégration hybride de matériaux actifs sur silicium. Parmi les travaux de conception, nous avons d'abord utilisé la méthodes des ondes planes et la méthode des différences finies (FDTD) pour concevoir une série de cavités SOI à hétérostructures, mécaniquement robustes, infiltrées par des liquides d’indices (n environ 1,5), présentant des longueurs d'onde de résonance dans la gamme des télécommunications (1,3 μm - 1,6 μm), des facteurs de qualité de plusieurs dizaines de milliers, et des volumes modaux proches de 0,03 (lambda/n)3. Nous avons ensuite étudié analytiquement et numériquement le couplage entre une cavité à cristaux photoniques à fente et un guide d'onde à fente par la théorie des modes couplés, complétée par des simulations FDTD, qui ont permis de confirmer la possibilité d'exciter efficacement les modes de fente des cavités à partir d'un guide externe. Enfin, nous avons étudié numériquement et semi-analytiquement des géométries de molécules photoniques constituées de deux cavités à cristaux photoniques à fentes couplées, dont l’écart fréquentiel entre les supermodes a pu être ajusté en amplitude et en signe. Nous avons utilisé une méthode perturbative (« Tight binding ») pour estimer les distributions spatiales des modes des molécules photoniques et prédire leurs fréquences dans plusieurs configurations de cavités à cristaux photoniques à fentes couplées.Ce travail exploratoire a été complété par une partie expérimentale qui a porté sur l'étude d'une famille de cavités de hétérostructure à cristaux photoniques à fente. Les cavités à cœur creux fabriquées ont montré des facteurs de qualité (Q) de plusieurs dizaines de milliers, associés à des volumes modaux de l’ordre de V=0,03 (λ/n)^3 après infiltration de la fente et des trous des structures par des liquides d'indice de réfraction proches de 1,46. Des facteurs Q/V supérieurs à 600 000 et atteignant 1 000 000 dans le meilleur des cas (vers lambda=1,3µm) ont ainsi été observés. Cette phase expérimentale préliminaire a donné ensuite lieu à deux types de développements.Tout d'abord, les propriétés des cavités à cristaux photoniques à fentes ont été étudiées pour des applications en détection d'indice en volume, et testées en utilisant différents liquides d'indice de réfraction compris entre 1,345 à 1,545. Les résonateurs étudiés ont présenté des sensibilités de ~ 235 nm / RIU et des facteur de mérite de détection d'indice de l’ordre de 3700, à l’état de l’art pour des résonateurs silicium intégrés à cœur creux.Dans une autre direction, le potentiel des résonateurs diélectriques à fente a été exploré en vue d’une intégration des matériaux actifs sur silicium. Un polymère dopé aux nanotubes de carbone semiconducteurs a été déposé comme matériau de couverture en vue d’étudier le renforcement de la photoluminescence (PL) des nano-émetteurs sous pompage optique vertical à lambda=740nm. Les expériences conduites ont permis de corréler le renforcement de la PL des nanotubes avec les modes de résonance des cavités et de démontrer le couplage partiel de cette PL vers des guides SOI longs de plusieurs millimètres (collection par la tranche vers lambda=1.3µm), apportant une preuve de principe d’une possible intégration des nanotubes émetteurs en photonique sur siliciumThis Ph.D. work is a contribution to the modeling and the experimental study of slot photonic crystal cavities for hybrid on-silicon integration. Among the design works, we first have used plane the wave expansion and finite-difference time-domain methods to design a series of mechanically robust (non-free membrane) SOI slot photonic crystal heterostructure cavities with resonance wavelengths in the telecommunication range, i.e. from 1.3 µm – 1.6 µm, with Q-factors of around several tens of thousands and mode volumes around 0.03(lambda/n)^3 after being infiltrated by cladding materials with typical index values around 1.5. We have then analytically and numerically studied the coupling between a slot photonic crystal cavity and a slot photonic crystal waveguide by using the coupled mode theory and FDTD simulation. Then we confirmed the ability to excite the cavity slot modes from a waveguide by using FDTD simulation. Finally, as a preliminary step towards the use of several coupled slotted cavities for future hybrid integration schemes, we have numerically and semi-analytically investigated photonic molecules made of two coupled slot photonic crystal cavities providing two different supermodes (bonding and antibonding ones) with controllable wavelength splitting. We successfully employed the tight-binding (TB) approach, which relies on the overlap of the two tightly confined cavity electric fields, to predict the supermodes frequencies and spatial distributions in several coupled slot photonic crystal cavity configurations.This exploratory work was supplemented by an experimental part, which focused on the investigation of a family of slot photonic crystal heterostructure cavities. The fabricated silicon on insulator hollow core cavities showed quality factors of several tens of thousands, i.e. from 18,000 to 31,000 and mode volume V of ~0.03(λ/n)3 after being infiltrated with liquids of ~1.46 refractive index, yielding Q/V ratio larger than 600,000, and reaching 1,000,000 in the best case (at λ ≈ 1.3 μm).This preliminary experimental stage gave rise to two types of additional developments.Firstly, the properties of the studied slot photonic crystal cavities have been investigated for index sensing applications by using different liquids with refractive index values ranging from 1.345 to 1.545. The considered photonic crystal resonators have demonstrated quality factors of several tens of thousands with sensitivities of ~235 nm/RIU and index sensing FOMs around 3,700, i.e. at the state of the art considering hollow core silicon integrated resonators.Secondly, in the view of the integration of active materials on silicon, the potential of these hollow core nanoresonators has been considered to enhance the photo-luminescence (PL) of semiconductor single-walled carbon nanotubes (SWNTs) integrated in thin films deposited on top of silicon. We have brought the first experimental demonstration of SWNTs PL collection (around lambda=1.28 µm) under vertical pumping at short wavelength (lambda=740 nm) from a slotted resonator into millimeter long integrated silicon waveguides, providing a first proof-of-concept step towards nanotube/Si-PhC integration as an active photonic platform. The reported works demonstrate the feasibility of integrating telecommunication wavelength nanotube emitters in silicon photonics as well as emphasize the role of slot photonic crystal cavities for on-chip hybrid integration
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De, Nobriga Charles. "Linear and nonlinear optics in coupled waveguide arrays". Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589645.
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The following thesis is comprised of four main areas of work. These are centred around the experimental observation of phenomena associated with both linear and non-linear optics in silicon photonic-wires. As a comparison, I also discuss a similar coupled-waveguide system; dual-core hollow-core photonic crystal fibre. To introduce the reader to this work, the first chapter will recap some undergraduate level theory; a general introduction to optical waveguides. It is not intended to be a complete theoretical picture, as many beautiful texts on optics already exist [1–3]. This chapter concerns itself only with the aspects of optics with which the author was intimately aware of throughout the completion of this thesis. Thereafter, the chapters become specific to the particular experiments undertaken. Each one follows a simple framework: examination of the relevant theory, extending upon that already discussed in the first chapter, a literature review and finally a discussion of the work I completed within this thesis. Chapter 2 is the only chapter not related to silicon based photonics. Here I discuss dual-core hollow-core photonic crystal fibres; including guidance mechanisms, fabrication methods and the numerical modelling techniques employed in my work. I will compare these numerical results to experimental results taken by colleagues at the university of Bath. Chapter 3 analyses linear propagation in arrays of silicon photonic wires. I extend the simple picture of light propagating in waveguides to discuss the di↵erent types of dispersion inherent in this system and how dispersion tailoring can be achieved; with reference to the other literature on this topic. Experimental results are examined and discussed. Chapters 4 and 5 discuss non-linear propagation in silicon photonic wire arrays; modulation instability and spatio-temporal solitons respectively. In each case I extend the ideas on non-linearity presented in Chapter 1 to explain both modulation instability and optical solitons. Detailed descriptions of the experiments undertaken, and associated numerical modelling completed are then discussed. Whilst the work I present is incomplete, I will discuss subsequent work performed by my colleagues at the University of Bath based on my initial work. Finally, Chapter 6 draws together my conclusions.
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Frank, Ian Ward. "Integrated filters for the on-chip silicon photonics platform". Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11205.
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We investigate the properties of integrated dielectric filters for the purposes of on-chip routing of photons. We started with the use of high quality factor tunable photonic crystal nanobeam cavities and moving on to examine a new class of reflection based reverse designed filters that maintain the footprint of a waveguide while allowing for arbitrary amplitude and phase response.Engineering and Applied Sciences
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Tjioe, Fidelia. "Evaluation of optical solder for fiber-to-waveguide coupling in silicon photonics". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45352.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.Includes bibliographical references (leaves 57-59).
Copper interconnects have shown its limit to meet the bandwidth demand even in the short reach applications due to its increase power consumption, RC delay, EMI, crosstalk and other effects which are aggravated as dimension shrinks. Despite efforts to increase the system performance, e.g. by multicore technology, migration to photonics is unavoidable, as it can give much superior performance. The major impediment to the wide-use of photonics is the cost. Three major components that contribute to the cost escalation are the absence of integrable light source, fast modulator, and effective fiber to waveguide coupler. The latest issue was addressed in this work. Coupling light efficiently from fiber to waveguide is challenging because of the size (6[mu]m core diameter for fiber, 500nm for waveguide), shape, and refractive index (~1.5 for fiber, 3.5 for waveguide) differences. Optical solder was proposed as the gap filler in between the fiber and waveguide to account for the fabrication uncertainties. Together with an inverse taper structure patterned in the waveguide end, the coupling loss was much reduced from 7.5dB (direct butt-coupling), to less than IdB. Besides, optical solder increases the reliability of device, as it prevents moisture and dust from impairing the optically active area of the die. Its fabrication is also integrable with the current CMOS technology. The configuration allows high density optical interconnect at the edges of the die; together with the electrical interconnect spreading across the area of the chip. All these make this system very good potential coupling method to solve one of the major impediments above, and thus enable the widespread use of electronic-photonic ICs.
by Fidelia Tjioe.
M.Eng.
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Barreto, Raúl E. "Fabrication of optical-mode converters for efficient fiber-to-silicon-waveguide couplers". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/41249.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2007.Includes bibliographical references (leaves 71-73).
Optical-mode converters are needed to efficiently couple light from an optical fiber to a photonic circuit by matching and transforming the propagating modes. This work is based on a horizontally-tapered coupler, in which light from an optical fiber is coupled into a large polymer waveguide and then gradually transferred to a smaller silicon waveguide whose width increases with distance along the guide. Several devices were designed and fabricated to measure the efficiency of the coupler. E-beam exposure doses and writing strategies were optimized to create the tapered silicon waveguides. A fabrication process was developed to form the polymer waveguides without etching the underlying silicon, and a set of marks was created to achieve sub-micron alignment between the two waveguides. Fabrication results showed that the coupler successfully transfers light between the two waveguides and that there is low loss in the polymer. A more accurate characterization of the coupler's efficiency was delayed due to fabrication problems not related to the developed process.
by Raúl E. Barreto.
M.Eng.
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Lea, Erik. "Photoelastic waveguides in bulk silicon and Si(1-x)Gex heterostructures". Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/843947/.
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A theoretical and experimental investigation into the characteristics of photoelastic optical waveguides in bulk silicon and Si1-xGex/Si heterostructures is presented. This is the first experimental demonstration of this type of waveguide in these material structures. The bulk silicon structures are also the first demonstration of channel waveguides defined using only photoelastic confinement. The photoelastic constants of silicon and Si1-xGex, which give the change in refractive index with strain, are calculated from the strain-induced shifts in the energy band structure of silicon and germanium which modifies their extinction coefficient, from which the strain-induced refractive index changes are found from the Kramers-Kronig relations. A finite element model of the waveguide structures is presented which uses the calculated photoelastic constants to determine the refractive index profiles of the waveguides. Subsequently, finite difference calculations are used to calculate the optical mode profiles of the waveguides. Photoelastic waveguides are fabricated by depositing SiNy stressor films onto bulk silicon and Si1-xGex/Si heterostructures which are subsequently cleaved and polished to produce waveguide facets before narrow stressor stripes are defined from the SiNy films using photolithography and wet etching. The characteristics of the waveguides are investigated at wavelengths of 1.15mum and 1.523mum. Measurements show that there is always one guiding region outside each edge of the stressor stripe. The Si1-xGex/Si heterostructures also allow a third mode to be confined under the centre of the stressor stripe, and the relative intensity and the distance between the guided modes is controlled by the stripe width, in good accordance with the modelling results. These structures are interesting in that up to three guiding regions can be defined by the deposition of one stressor stripe on the waveguide surface, which provides a particularly simple and compact way of fabricating waveguide couplers. An interferometer is used to study the force generated by the SiNy stressor layers. It is shown that the as-deposited stressors produce low and poorly defined stresses, although significant forces of up to 2-3.106 dyn/cm are measured after rapid thermal annealing of the structures. Annealing of photoelastic waveguides in bulk silicon show a corresponding increase in photoelastic confinement which produces waveguides with excess losses of down to 4.3dB/cm. Photoelastic waveguides in Si1-xGex/Si heterostructures, due to the additional confinement from the heterojunction, are reported with zero excess losses. At 1.15mum, the band-edge absorption increases the waveguide propagation losses by up to several dB/cm, and the waveguides show multimode behaviour, making these structures unsuitable for applications at this wavelength. At 1.523mum, however, measurements show low excess propagation losses and single-mode behaviour, and they exhibit a low degree of birefringence. The simple fabrication process and compact design of these structures make them appropriate for optoelectronic intragration, and several possible applications for photoelastic waveguides in optical devices are suggested.
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Hegde, Shashikant G. "Investigation of optical loss changes in siloxane polymer waveguides during thermal curing and aging". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22531.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2008.Committee Chair: Sitaraman, Suresh; Committee Member: Chang, Gee-Kung; Committee Member: Colton, Jonathan; Committee Member: Joshi, Yogendra; Committee Member: Swaminathan, Madhavan; Committee Member: Thompson, Patrick.
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Harvey, Christopher T. "Silicon-on-insulator waveguide structures for electro-optic applications /". Online version of thesis, 2005. http://hdl.handle.net/1850/5198.
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Fernández, Vicente Juan. "Reconfigurable Reflective Arrayed Waveguide Grating on Silicon Nitride". Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/165783.
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[ES] La presente tesis se ha centrado en el modelado, diseño y demonstración experimental por primera vez del dispositivo Reconfigurable Reflective Arrayed Waveguide Grating (R-RAWG). Para la consecución de este dispositivo que tiene posibilidades de uso en la espectrometría, una plataforma de nitruro de silicio llamada CNM-VLC se ha usado, ya que este material permite operar en un gran ancho de banda. Esta plataforma posee ciertas limitaciones y los elementos necesarios para el funcionamiento de este dispositivo tenían un performance bajo. Por ello, se ha desarrollado y validado una metodología que ha permitido obtener mejores divisores. Además, se ha diseñado un inverted taper que ha mejorado considerablemente el acoplo de luz al chip. Esto ha sido gracias a un exhaustivo análisis de opciones existentes en la literatura que también ha permitido escoger la mejor opción para realizar un espejo reconfigurable en la plataforma sin cambiar ni añadir ningún proceso de fabricación. Se han demostrado espejos reconfigurables gracias a utilizar divisores ópticos realimentados y también se ha desarrollado códigos que predicen el comportamiento del dispositivo experimentalmente. Con todo el trabajo realizado, se ha diseñado un R-RAWG para que pudiera operar en un gran ancho de banda y que los actuadores de fase no tuvieran peligro de estropearse. También se ha desarrollado un código para el modelado del R-RAWG que permite imitar la fabricación de estos dispositivos y que, gracias a esto, se ha desarrollado un método o algoritmo llamado DPASTOR, que usa algoritmos usados en machine learning, para optimizar la respuesta con tan sólo la potencia óptica de salida. Finalmente, se ha diseñado una PCB para poder conectar eléctricamente el chip fotónico y se ha desarrollado un método de medida que ha permitido tener una respuesta estable consiguiendo demostrar multitud de respuestas de filtros ópticos con el mismo dispositivo.[CAT] La present tesi s'ha centrat en el modelatge, disseny i demonstració experimental per primera vegada del dispositiu Reconfigurable Reflective Arrayed Waveguide Grating (R-RAWG). Per a la consecució d'aquest dispositiu que té possibilitats d'ús en l'espectrometria, una plataforma de nitrur de silici anomenada CNM-VLC s'ha usat ja que aquest material permet operar en una gran amplada de banda. Aquesta plataforma posseeix certes limitacions i els elements necessaris per al funcionament d'aquest dispositiu tenien un performance baix. Per això, s'ha desenvolupat i validat una metodologia que ha permés obtindre millors divisors i també, gràcies als processos de fabricació, s'ha dissenyat un acoplador que ha millorat considerablement l'acoble de llum al xip. Això ha sigut gràcies a un exhaustiu analisis d'opcions existents en la literatura que també ha permés triar la millor opció per a realitzar un espill reconfigurable en la plataforma sense canviar ni afegir cap procés de fabricació. S'han demonstrat espills reconfigurables gràcies a utilitzar divisors realimentats i també s'ha desenvolupat codis que prediuen el comportament del dispostiu experimentalment. Amb tot el treball realitzat, s'ha dissenyat un R-RAWG fent ús de determinades consideracions perquè poguera operar en una gran amplada de banda i que els actuadors de fase no tingueren perill de desbaratar-se. També s'ha desenvolupat un codi per al modelatge del R-RAWG que permet imitar la fabricació d'aquests dispositius i que, gràcies a això, s'ha desenvolupat un mètode o algorisme anomenat DPASTOR, que usa algorismes usats en machine learning, per a optimitzar la resposta amb tan sols la potència òptica d'eixida. Finalment, s'ha dissenyat una PCB per a poder connectar elèctricament el xip fotònic i s'ha desenvolupat un mètode de mesura que ha permés tindre una resposta estable aconseguint demostrar multitud de respostes de filtres òptics amb el mateix dispositiu.
[EN] This thesis is focused on the modelling, design and experimental demonstration for the first time of Reconfigurable Reflective Arrayed Waveguide Grating (R-RAWG) device. In order to build this device, that can be employed in spectrometry, a silicon nitride platform termed CNM-VLC has been chosen since this material allows to operate in broad range of wavelengths. This platform has the necessary elements, but some limitations because the operation of this device had a low performance. Therefore, a methodology has been developed and validated, which has allowed to obtain better splitters. Also an inverted taper has been designed, which has considerably improved the coupling of light to the chip. This has been possible thanks to an exhaustive analysis of existing options in the literature, that has allowed choosing the best option to make a reconfigurable mirror on the platform without changing or adding new manufacturing steps. Reconfigurable mirrors have been demonstrated by using feedback splitters. Furthermore, codes have been developed to predict the behaviour of the actual device. With all the work done, a R-RAWG has been designed by using certain considerations so that it can operate over a broad wavelength range and the phase actuators are not in danger of being damaged. A code has also been developed for the modelling of the R-RAWG, which allows manufacturing imperfections to be considered, thanks to this, a method or algorithm called DPASTOR has been developed. DPASTOR resembles machine learning to optimise the response by just using the optical output power. Finally, a PCB and an assembly with the chip interconnected to it have been made and designed. Moreover, a measurement method has been developed, which has made it possible to have a stable response and to demonstrate a multitude of optical filter responses with the same device.
Fernández Vicente, J. (2021). Reconfigurable Reflective Arrayed Waveguide Grating on Silicon Nitride [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/165783
TESIS