Dissertations / Theses on the topic 'Silicon-on-insulator waveguides'
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1
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.
2
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.
3
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.
4
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.
5
Chan, Seong Phun. "Third order Bragg grating filters in silicon-on-insulator waveguides." Thesis, University of Surrey, 2005. http://epubs.surrey.ac.uk/842993/.
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The subject of this thesis is the design, analysis, fabrication and characterisation of third order Bragg grating optical filters on silicon-on-insulator (SOI) rib waveguides. New design guidelines for small cross sectional SOI waveguides have been proposed and described to address the issue of satisfying polarisation independence and single mode conditions simultaneously. This waveguide design will be used as a building block for the realisation of Bragg grating filters. The reflection spectral response of the deep Bragg grating operating in a third diffraction order on a single mode rib SOI waveguide has been studied theoretically using Floquet-Bloch Theory (FBT) developed in Politecnico di Bari, Italy in comparison with optical modelling software utilising Coupled Mode Theory (CMT). A series of Bragg gratings with different grating etch depths and lengths were fabricated at Southampton University to investigate the agreement between experimental results with theoretical predictions. The wavelength tuning capability of these Bragg grating filters in SOI waveguide structures were also investigated and implemented using the thermo-optic effect, through Joule heating of thin film aluminium heaters situated on top of the rib structure. The SOI rib waveguides with 1.5mum height are designed to exhibit polarisation independence and single mode operation. The Bragg grating filter is designed to operate at a wavelength of 1.55mum with a grating period of 689nm. The less rigorous fabrication tolerance of third order grating in comparison with that required by 228nm first order gratings is highly desirable only at the expense of slightly lower maximum reflectivity. The maximum reflectivity measurements of approximately 0.42 for third order grating are in agreement with theoretical prediction by FBT. The Bragg grating filters were thermally tuned to shift the Bragg resonance wavelength by up to 3.5nm with heater power of approximately 190mW. The tuning range of the filter is inhibited by the short lifetime of the heater caused by electromigration. At the time this work was carried out, this is the first demonstration of thermo-optic tuning through an integrated heating element, of third order Bragg grating filters based on small cross sectional SOI waveguide. The temperature sensitivity of the Bragg grating filters was analysed using a 2-D finite element method (FEM) and was consistent with the experimental results.
6
Waugh, Peter Michael. "First order Bragg grating filters in silicon on insulator waveguides." Thesis, University of Surrey, 2008. http://epubs.surrey.ac.uk/843865/.
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The subject of this thesis is the design; analysis, fabrication and characterisation of first order Bragg Grating optical filters in Silicon-on-Insulator (SOI) planar waveguides. It is envisaged that this work will result in the possibility of Bragg Grating filters for use in Silicon Photonics. It is the purpose of the work to create as far as is possible flat surface waveguides so as to facilitate Thermo-Optic tuning and also the incorporation into rib-waveguide Silicon Photonics. The spectral response of the shallow Bragg Gratings was modelled using Coupled Mode Theory (CMT) by way of RSoft Gratingmod TM. Also the effect of having a Bragg Grating with alternate layers of refractive index 1.5 and 3.5 was simulated in order to verify that Silica and Silicon layered Bragg Gratings could be viable. A series of Bragg Gratings were patterned on 1.5 micron SOI at Philips in Eindhoven to investigate the variation of grating parameters with a) the period of the gratings b) the duty cycle (or mark to space ratio) of the gratings and c) the length of the region converted to Bragg Gratings (i.e. the number of grating period repetitions). One set of gratings were thermally oxidised at Philips in Eindhoven (this was to simulate the effects of oxidising Porous Silicon) and another set were ion implanted with Oxygen ions at the Ion Beam Facility, University of Surrey. The gratings were tested and found to give transmission minima at approximately 1540 nanometres and both methods of creating flat surfaces were found to give similar minima. Atomic Force Microscopy was applied to the grating area of the Ion as Implanted samples in the ATI, University of Surrey, which were found to have surface undulations in the order of 60 nanometres.
7
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.
8
Zhang, Fan. "Sinusoidal anti-coupling symmetric strip waveguides on a silicon-on-insulator platform." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62885.
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The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
9
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.
10
Powell, Olly, and 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.
11
Powell, Olly. "Fabrication of Micro-Mirrors in Silicon Optical Waveguides." Thesis, Griffith University, 2004. http://hdl.handle.net/10072/365595.
Full textAbstract:
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.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Microelectronic Engineering
Full Text
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Kaplan, Ali Emre. "Study of Periodic and Quasi-Periodic Structures in Silicon-on-Insulator." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11038/.
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In this thesis, a numerical design approach has been proposed and developed based on the transmission matrix method in order to characterize periodic and quasi-periodic photonic structures in silicon-on-insulator. The approach and its performance have been extensively tested with specific structures in 2D and its validity has been verified in 3D.
13
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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Qian, Yusheng. "Compact Trench Based Bend and Splitter Devices for Silicon-on-Insulator Rib Waveguides." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/1784.
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Bends and splitters are typically the fundamental limiting waveguide components in reducing the size of planar lightwave circuits (PLCs) based on waveguides that have a low core/clad refractive index contrast, such as silicon-on-insulator (SOI) rib waveguides. This dissertation presents a solution to this problem in the form of trench-based bends (TBBs) and trench-based splitters (TBSs). Emphasis is placed on experimental demonstration of these components and their integration into practical devices exhibiting significant size reduction. First, a compact and low loss silicon-on-insulator rib waveguide 90◦ TBB is demonstrated based on an etched vertical interface and total internal reflection (TIR) realized by a trench filled with SU8. The measured loss for TE polarization is 0.32 dB ± 0.02 dB/bend at a wavelength of 1.55 μm, which is the best reported in literature. Next, 90◦ TBSs are reported in which each splitter occupies an area of only 11 μm x 11 μm. These components require fabrication of trenches with a nearly 10:1 aspect ratio. A variety of single TBSs are fabricated having different trench widths. The relative amount of power directed into the transmission and reflection arms of the splitters is measured. The TBS reflection and transmission ratio agrees with three dimensional (3D) finite difference time domain (FDTD) predictions. An 82 nm wide trench filled with index matching fluid is experimentally shown to have a reflection/transmission splitting ratio of 49/51 at a wavelength of 1550 nm. To increase the fabrication yield of TBSs, the splitter angle is modified from 90◦ to 105◦, which permits the trench width to be increased to 116 nm for a 50/50 splitter using SU8 as the trench fill material. The fabrication and measurement of compact 105◦ TBBs and TBSs are reported followed by their integration into 1 x 4, 1 x 8, and 1 x 32 trench-based splitter networks (TBSNs). The measured total optical loss of the 1 x 32 TBSN is 9.15 dB. Its size is only 700 μm x 1600 μm for an output waveguide spacing of 50 μm. Finally, a compact SOI trench-based ring resonator (TBRR) composed of 90◦ TBBs, TBSs, and rib waveguides is demonstrated. A TBRR with a ring circumference of 50 μm occupies an area of 20 x 20 μm. The free spectral range (FSR) is as large as 14 nm. By changing the trench fill material from SU8 (n = 1.57) to index fluid (n = 1.733), the peak wavelength can be shifted ∼2 nm. Fabricated TBSNs and TBRRs demonstrate that large size reductions are possible for devices based on TBBs and TBSs. The net result is bend and splitter configurations with a size that is essentially independent of core/clad refractive index contrast. The approach developed in this dissertation is applicable to a wide range of waveguide material systems that have small core/clad refractive index contrast.
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Sanchis, Kilders Pablo. "Coupling techniques between dielectric waveguides and planar photonic crystals." Doctoral thesis, Universitat Politècnica de València, 2008. http://hdl.handle.net/10251/1854.
Full textAbstract:
El objetivo de esta tesis es la investigación de estructuras y técnicas de acoplo para minimizar las pérdidas de acoplo entre guías dieléctricas y cristales fotónicos planares. En primer lugar se ha estudiado el modelado del acoplo entre guías dieléctricas y guías en cristal fotónico así como la influencia de los principales parámetros del cristal en la eficiencia de acoplo. Se han obtenido expresiones cerradas para las matrices de reflexión y transmisión que caracterizan totalmente el scattering que ocurre en el interfaz formado entre una guía dieléctrica y una guía en cristal fotónico. A continuación y con el fin de mejorar la eficiencia de acoplo desde guías dieléctrica de anchura arbitraria, se ha propuesto como contribución original una técnica de acoplo basada en la introducción de defectos puntuales en el interior de una estructura de acoplo tipo cuña realizada en el cristal fotónico. Diferentes soluciones, incluida los algoritmos genéticos, han sido propuestas con el objetivo de conseguir el diseño óptimo de la configuración de defectos. Una vez conseguido un acoplo eficiente desde guías dieléctricas a guías en cristal fotónico, se ha investigado el acoplo en guías de cavidades acopladas. Como contribución original se ha propuesto una técnica de acoplo basada en la variación gradual del radio de los defectos situados entre cavidades adyacentes. Además, se ha realizado un riguroso análisis en el dominio del tiempo y la frecuencia de la propagación de pulsos en guías acopladas de longitud finita. Dicho estudio ha tenido como objetivo la caracterización de la influencia de la eficiencia del acoplo en los parámetros del pulso. Finalmente, se han presentado los procesos de fabricación y resultados experimentales de las estructuras de acoplo propuestas.Sanchis Kilders, P. (2005). Coupling techniques between dielectric waveguides and planar photonic crystals [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1854
Palancia
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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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Wilson, Cynthia 1974. "A free-carrier based silicon on insulator waveguide attenuator /." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32975.
Full textAbstract:
All solid-state switches and attenuators are becoming increasingly popular over their mechanical counterparts. Their advantages include smaller size, no moving parts, and faster response times. The device presented here is a silicon on insulator waveguide attenuator, its operation is based on free-carrier absorption of photons. Free-carriers are provided by forward biasing a PIN diode structure integrated in a single mode rib waveguide where the guided mode propagates in the intrinsic region. The device was optimized optically using CAD tools to provide off-state losses of less than 1dB. The PIN diode electrical structure was also optimized to for a maximum power consumption of 1W at maximum attenuation. Good agreement of the theory developed was found when compared to experimental measurements of fabricated prototypes of similar structure. Fabrication and testing of devices according to the specifications arrived at in this thesis is suggested for future work.
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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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Dai, Daoxin. "Designs and simulations of silicon-based microphotonic devices." Doctoral thesis, Stockholm: Division of Electromagnetic Theory, Royal Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226.
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Tashtush, Aktham Atallah Mofleh. "Characterization of integrated Bragg gratings in silicon-on-insulator." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/7670/.
Full textAbstract:
Silicon-on-insulator (SOI) is rapidly emerging as a very promising material platform for integrated photonics.
As it combines the potential for optoelectronic integration with the low-cost and large volume manufacturing capabilities and they are already accumulate a huge amount of applications in areas like sensing, quantum optics, optical telecommunications and metrology.
One of the main limitations of current technology is that waveguide propagation losses are still much higher than in standard glass-based platform because of many reasons such as bends, surface roughness and the very strong optical confinement provided by SOI.
Such high loss prevents the fabrication of efficient optical resonators and complex devices severely limiting the current potential of the SOI platform.
The project in the first part deals with the simple waveguides loss problem and trying to link that with the polarization problem and the loss based on Fabry-Perot Technique.
The second part of the thesis deals with the Bragg Grating characterization from again the point of view of the polarization effect which leads to a better stop-band use filters.
To a better comprehension a brief review on the basics of the SOI and the integrated Bragg grating ends up with the fabrication techniques and some of its applications will be presented in both parts, until the end of both the third and the fourth chapters to some results which hopefully make its precedent explanations easier to deal with.
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Bazin, Alexandre. "III-V semiconductor nanocavities on silicon-on insulator waveguide : laser emission, switching and optical memory." Paris 7, 2013. http://www.theses.fr/2013PA077050.
Full textAbstract:
La photonique sur silicium constitue une plateforme idéale pour transmettre et distribuer des signaux optiques au sein d'une puce et sur de longues distances sans pertes excessives. L'intégration de semiconducteurs NIA sur des circuits photonique en silicium est un projet excitant mais ambitieux, que nous avons mené en combinant le meilleur de l'optoélectronique des semiconducteurs III-V et des technologies photonique en siliicium-sur-isolant (SOI en anglais). Afin de pouvoir remplacer les interconnexions métalliques existantes par des interconnexion optiques, nous nous sommes efforcés d'utiliser les objets ayant les dimensions les plus petites et consommant les plus petites énergies comme peuvent l'être les nanocavités en Cristaux Photoniques incorporant des matériaux actif en III-V. Cette thèse visait à conceptualiser, fabriquer et étudier expérimentalement des structures hybrides I V/circuit photonique SOI, où une couche de III-V, collé adhésivement à quelques centaines de μm du silicium, est gravé en une cavité optique de type «nanobeam » et résonante autour de 1,5 μm. Les principaux résultats de ce travail sont les démonstration 1) d'une efficacité de couplage entre la cavité et le guide d'onde SOI facilement ajustable, pouvant excéder 90% lorsque les conditions d'accord de phase sont remplies, 2) de l'émission laser en régime continue avec des puits quantiques via la passivation des surfaces, et 3) d'une mémoire optique de durée supérieure à 2s avec des énergies de commutations ultra-faibles (~0. 4 fJ). Nous présentons aussi un modèle pour fabriquer des cavités « nanobeam » de facteurs Q très élevés, encapsulées dans un matériau bas indiceSilicon photonics constitutes an ideal platform for conveying and routing optical signals, within a chip, and this, over mm long distances with very low losses. The integration of III-V semiconductors onto silicon-on-insulator (SOI) photonic circuits is an exciting but challenging task, which we took-up by combining the best of both III-V optoelectronic and Silicon photonic technologies. In order to be able to use optical interconnects as a replacement technology of current metallic interconnects, we strove for the smallest footprint and lowest energy consuming objects which can be Photonic Crystal nanocavities embedding III-V active material. This thesis aimed at designing, fabricating and studying experimentally hybrid III-V/SOI Photonic Circuit structures, where a III-V layer, bonded adhesively at a few 100's of nm from silicon, is patterned into a nanobeam cavity of optical resonance around 1. 5 μm. The main achievements of this work are the demonstration of 1) an easily adjustable coupling efficiency between the cavity and the SOI waveguide, which can exceed 90% when the phase-matching condition are fulfilled, 2) the continuous wave laser emission with quantum well materials through surface passivation, and 3) an optical memory lasting more than 2 s with ultra- low switching energy (~0. 4 fJ). We also present in detail the fully analytical model to fabricate high-Q factor nanobeam cavities encapsulated in a low-index material
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Bazin, Alexandre. "III-V Semiconductor Nanocavitieson Silicon-On-Insulator Waveguide : Laser Emission, Switching and Optical Memory." Phd thesis, Université Paris-Diderot - Paris VII, 2013. http://tel.archives-ouvertes.fr/tel-01007643.
Full textAbstract:
La photonique sur silicium constitue une plateforme idéale pour transmettre et distribuer des signaux optiques au sein d'une puce et sur de longues distances sans pertes excessives. L'intégration de semiconducteurs III-V sur des circuits photonique en silicium est un projet excitant mais ambitieux, que nous avons mené en combinant le meilleur de l'optoélectronique des semiconducteurs III-V et des technologies photonique en siliicium-sur-isolant (SOI en anglais). Afin de pouvoir remplacer les interconnexions metalliques existantes par des interconnexion optiques, nous nous sommes efforcés d'utiliser les objets ayant les dimensions les plus petites et consommant les plus petites énergies comme peuvent l'être les nanocavités en Cristaux Photoniques incorporant des matériaux actifs en III-V. Cette thèse visait à conceptualiser, fabriquer et étudier expérimentalement des structures hybrides III-V/circuit photonique SOI, où une couche de III-V, reportée par collage adhésif à quelques centaines de nm du silicium, est gravée en une cavité optique de type cristal photonique " nanobeam " et résonante autour de 1.5 μm. Les principaux résultats de ce travail sont les démonstration 1) d'une efficacité de couplage entre la cavité et le guide d'onde SOI facilement ajustable, pouvant excéder 90% lorsque les conditions d'accord de phase sont remplies, 2) de l'émission laser en régime continue avec des puits quantiques via la passivation des surfaces, et 3) d'une mémoire optique de durée supérieure à 2s avec des énergies de commutations ultrafaibles (~0.4 fJ). Nous présentons aussi un modèle pour fabriquer des cavités " nanobeam " de facteurs Q très élevés, encapsulées dans un matériau bas indice.
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Lim, Soon Thor. "Flat spectral response arrayed waveguide grating (AWG) in silicon-on-insulator (SOI) via ion implantation." Thesis, University of Surrey, 2005. http://epubs.surrey.ac.uk/844540/.
Full textAbstract:
This thesis proposed and demonstrated a flat-spectral response Arrayed Waveguide Grating (AWG) in Silicon-on-Insulator (SOI). The response exhibits a flat spectral of approximately 0.5nm with a crosstalk level of round -3dB. The high crosstalk is due to the phase errors as a result of fabrication tolerance and errors. Two main errors were identified. Firstly, the systematic errors of waveguide rib width and etched depth and secondly, the random variation of photomask resolution which was subjected to fabrication equipment in Southampton University. These errors have been investigated and the observations of the analysis were consistent with the experimental result. The AWG is designed to operate at a centre wavelength of 1.55mum at a grating order of 52 with path length differences of 23.62mum. The rib waveguides of the array are designed to operate as singlemode waveguides and to exhibit minimum polarisation dependence. As this thesis is to proof of principle, additional optimisation of the AWG is not carried out. The main ideology of the design method is to introduce free carriers to parts of the waveguides across the grating arms to induce absorption. This will modify the shape the field distribution across the array waveguides from a Gaussian to a SINC function. By applying Fourier optics to the free space region of the AWG, this field profile is the inverse Fourier transforms of the required output field of the AWG, which is the flat spectral response. This method gives the robustness of tailoring the optical field distribution across the AWs by the appropriate choice of net doping concentration, and hence gives room for design flexibility without increasing the physical dimension of the AWG significantly. The potential of achieving a smaller SOI AWG device with the use of higher net dosage and the realisation of achieving a uniform doping concentration through multiple implantations has been discussed. Keywords: Arrayed Waveguide Gratings (AWG), Flat-spectral response, Ion Implantation, Rib waveguides, Silicon-on-insulator (SOI), Silicon photonics.
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Song, Jiguo. "Compact Trench-Based Silicon-on-Insulator Rib Waveguide 90-Degree and 105-Degree Bend and Splitter Design." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2547.pdf.
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Ehteshami, Nasrin. "Silicon Photonic Devices for Microwave Signal Generation and Processing." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34111.
Full textAbstract:
Silicon photonics as a one of the most promising photonic integration technologies has attracted many attentions in recent years. The major feature of this technology is its compatibility with complementary metal-oxide semiconductor (CMOS) processes which makes it possible to integrate optical and electronic devices in a same chip and reduce the cost significantly. Another reason of using silicon photonics is the high index contrast between the silicon core and silicon dioxide cladding which ensures the high density integration of photonic devices on a single chip. Monolithic integration with electronic and optical circuits makes silicon photonics technology suitable for numerous applications. One example is microwave photonics (MWP). MWP is an area that studies the interaction between microwave and optical signal for the generation, processing, control and distribution of microwave signals by means of photonics. Silicon photonics offers a reduction in footprint, losses, packaging cost and power dissipation in MWP systems.
This research in this thesis is focused on the design and fabrication of the silicon photonic devices for MWP signal processing and generation. Four MWP systems based on silicon photonic devices are proposed and experimentally demonstrated.
1) A single pass-band frequency-tunable MWP filter based on phase-modulation to intensity-modulation conversion in an optically pumped silicon-on-insulator (SOI) microring resonator (MRR) is designed and experimentally demonstrated. In the proposed filter, a phase-modulated optical signal is filtered by the SOI MRR, to have one first-order sideband suppressed by the MRR notch. The phase-modulated optical signal is converted to an intensity-modulated single-sideband (SSB) signal and detected at a photodetector (PD). The entire operation is equivalent to a single pass-band filter. The frequency tunability is achieved by tuning the resonance wavelength of the MRR, which is realized by optically pumping the MRR. A single pass-band MWP filter with a tunable center frequency from 16 to 23 GHz is experimentally demonstrated.
2) A broadband optically tunable MWP phase shifter with a tunable phase shift using three cascaded SOI MRRs that are optically pumped is designed and experimentally demonstrated. A microwave signal to be phase shifted is applied to an optical single-sideband (OSSB) modulator to generate an optical carrier and an optical sideband. The phase shift is introduced to the optical carrier by placing the optical carrier within the bandwidth of one resonance of the three cascaded MRRs. The experimental results show that by optically pumping the cascaded MRRs, a broadband MWP phase shifter with a bandwidth of 7 GHz with a tunable phase shift covering the entire 360o phase shift range is achieved.
3) A multi tap MWP filter with positive and negative coefficients using a silicon ring resonator modulator (RRM) is proposed and experimentally demonstrated. The RRM is designed and fabricated to operate based on the carrier depletion effect. The positive and negative coefficients are obtained by using opposite slopes of the modulation transmission response of the RRM. Two filter responses with two and three taps are experimentally demonstrated, showing the proof-of-principle for frequencies up to 18 GHz.
4) An approach to generate microwave signal based on enhanced four wave mixing (FWM) in an active silicon waveguide (SiWG) is studied. This SiWG is designed and fabricated, and the use of the active SiWG for MWP frequency multiplication to generate a frequency-sextupled millimeter-wave signal is experimentally demonstrated. Thanks to a reverse-biased p-n junction across the SiWG, the conversion efficiency of the FWM is improved, which leads to the improvement of the microwave frequency multiplication efficiency.
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Dupont, Tiphaine. "Réalisation de sources laser III-V sur silicium." Phd thesis, Ecole Centrale de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00604962.
Full textAbstract:
Le substrat SOI (Silicon-On-Insulator) constitue aujourd'hui le support de choix pour la fabrication de fonctions optiques compactes. Cette plateforme commune avec la micro-électronique favorise l'intégration de circuits photoniques avec des circuits CMOS. Néanmoins, si le silicium peut être utilisé de manière très avantageuse pour la fabrication de composants optiques passifs, il présente l'inconvénient d'être un très mauvais émetteur de lumière. Ceci constitue un obstacle majeur au développement de sources d'émission laser, briques de constructions indispensables à la fabrication d'un circuit photonique. La solution exploitée dans le cadre de cette thèse consiste à reporter sur SOI des épitaxies laser III-V par collage direct SiO2-SiO2. L'objectif est de réaliser sur SOI des sources lasers à cavité horizontale permettant d'injecter au moins 1mW de puissance dans un guide d'onde silicium inclus dans le SOI. Notre démarche est de transférer un maximum des fonctions du laser vers le silicium, dont les procédés sont familiers au monde de la micro-électronique. Dans l'idéal, le III-V ne devrait être utilisé que comme matériau à gain ; la cavité laser pouvant être fabriquée dans le silicium. Mais cette ligne de conduite n'est pas forcément aisée à mettre en œuvre. En effet, les photons sont produits dans le III-V mais doivent être injectés dans un guide silicium placé sous l'épitaxie. La difficulté est que les deux matériaux sont séparés par plus d'une centaine de nanomètres d'oxyde de collage faisant obstacle au transfert de photons. Le développement de lasers III-V couplés à un guide d'onde SOI demande alors de nouvelles conceptions du système laser dans son ensemble. Notre travail a donc consisté à concevoir un laser hybride III-IV / silicium se pliant aux contraintes technologiques du collage. En s'appuyant sur la théorie des modes couplés et les concepts des cristaux photoniques, nous avons imaginé, réalisé, puis caractérisé un laser à contre-réaction distribuée hybride (en anglais : " distributed feedback laser ", laser DFB). Son fonctionnement optique original, permet à la fois un maximum de gain et d'efficacité de couplage grâce à une circulation en boucle des photons du guide III-V au guide SOI. Sur ces dispositifs, nous montrons une émission laser monomode (SMSR de 35 dB) à température ambiante en pompage optique et électrique pulsé. Comme attendu, la longueur d'onde d'émission est dépendante du pas de réseau DFB. Les lasers fonctionnent avec une épaisseur de collage de silice de 200 nm, ce qui offre une grande souplesse quant au procédé d'intégration. Tous les lasers fonctionnent jusqu'à des longueurs de 150 μm (la plus petite longueur prévue sur le masque). Malgré les faibles niveaux de puissances récoltés dans la fibre lors des caractérisations, la prise en compte des pertes optiques induites pas les coupleurs fibres nous indique que la puissance réellement injectée dans le guide silicium dépasse le milliwatt. Notre objectif de ce point de vue est donc rempli. Malheureusement le fonctionnement des lasers en injection électrique continue n'a pas pu être obtenu dans les délais impartis. Cependant, les faibles densités de courant de seuil mesurées en injection pulsée (300A / cm2 à température ambiante sur les lasers de 550 μm de long) laissent présager un fonctionnement prochain en courant continu.
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"Optical properties and applications of silicon waveguides." 2002. http://library.cuhk.edu.hk/record=b5891085.
Full textAbstract:
Liang Tak Keung.Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references.
Abstracts in English and Chinese.
Abstract --- p.I
Acknowledgement --- p.IV
Table of contents --- p.V
List of figures --- p.VIII
Chapter Chapter 1: --- Introduction --- p.1
Chapter 1.1 --- Introduction to silicon waveguides --- p.2
Chapter 1.2 --- Introduction to characterization of silicon waveguides --- p.5
Chapter 1.3 --- Introduction to applications of silicon waveguides --- p.6
Chapter 1.4 --- Introduction to chapters --- p.7
References --- p.9
Chapter Chapter 2: --- Modal analysis of the single-mode silicon waveguide --- p.12
Chapter 2.1 --- Waveguide structure --- p.13
Chapter 2.2 --- Effective Index Method --- p.14
Chapter 2.3 --- Silicon waveguide modal analysis --- p.20
Chapter 2.4 --- Conclusion --- p.25
References --- p.26
Chapter Chapter 3: --- Optical dispersion --- p.27
Chapter 3.1 --- Introduction --- p.28
Chapter 3.1.1 --- Chromatic dispersion --- p.28
Chapter 3.1.2 --- Polarization-mode dispersion --- p.33
Chapter 3.2 --- Review of dispersion measurement technique --- p.35
Chapter 3.2.1 --- Chromatic dispersion measurement --- p.35
Chapter 3.2.2 --- Polarization-mode dispersion measurement --- p.39
Chapter 3.3 --- Measurement of chromatic dispersion in silicon waveguide --- p.40
Chapter 3.3.1 --- Experimental setup --- p.40
Chapter 3.3.2 --- Measurement theory --- p.41
Chapter 3.3.3 --- Results and discussions --- p.43
Chapter 3.4 --- Measurement of polarization-mode dispersion in silicon waveguide --- p.49
Chapter 3.4.1 --- Experimental setup --- p.49
Chapter 3.4.2 --- Simulation results --- p.50
Chapter 3.4.3 --- Results and discussions --- p.51
Chapter 3.5 --- Conclusion --- p.53
References --- p.54
Chapter Chapter 4: --- Nonlinear properties --- p.56
Chapter 4.1 --- Introduction --- p.57
Chapter 4.1.1 --- Nonlinear refractive index (optical Kerr effect) --- p.57
Chapter 4.1.2 --- Self-phase modulation --- p.58
Chapter 4.1.3 --- Two-photon absorption --- p.59
Chapter 4.1.4 --- Impact of nonlinearities on waveguides --- p.60
Chapter 4.2 --- Measurement of nonlinear refractive index n2 and TPA coefficient β2 --- p.61
Chapter 4.2.1 --- Nonlinear refractive index (n2) --- p.62
Chapter 4.2.2 --- TPA coefficient (β2) --- p.63
Chapter 4.2.3 --- Conclusion --- p.65
References --- p.66
Chapter Chapter 5: --- Loss in ion-implanted silicon waveguide --- p.67
Chapter 5.1 --- Introduction to ion implantation --- p.68
Chapter 5.2 --- Ion-implantation process --- p.70
Chapter 5.3 --- Loss measurement by Fabry-Perot interferometer --- p.72
Chapter 5.4 --- Results and discussions --- p.73
References --- p.75
Chapter Chapter 6: --- Silicon waveguide autocorrelator --- p.76
Chapter 6.1 --- Introduction on SHG and waveguide autocorrelation technique --- p.77
Chapter 6.2 --- Theory of TPA absorption --- p.79
Chapter 6.3 --- Two-photon-induced photocurrent in silicon waveguide --- p.80
Chapter 6.3.1 --- Device structure --- p.80
Chapter 6.3.2 --- Intensity dependent photocurrent generation --- p.81
Chapter 6.3.3 --- Theoretical modeling of photocurrent generation --- p.83
Chapter 6.4 --- Autocorrelation measurement of short pulses --- p.87
Chapter 6.4.1 --- Experimental setup --- p.87
Chapter 6.4.2 --- Results and discussions --- p.88
Chapter 6.5 --- Conclusion --- p.92
References --- p.93
Chapter Chapter 7: --- Conclusion and future works --- p.94
Chapter 7.1 --- Conclusion --- p.94
Chapter 7.2 --- Future works --- p.95
Appendices --- p.96
Appendix A: Silicon waveguide fabrication process capability at CUHK --- p.96
Appendix B: Matlab programs of EIM and TPA calculation --- p.100
Appendix C: Publications list --- p.104
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Li, Chung-pei, and 李鍾沛. "INVESTIGATION OF SELF ALIGNMENT SINGLE MODE RIDGE WAVEGUIDES BASED ON SILICON ON INSULATOR SUBSTRATES." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/2n62zg.
Full textAbstract:
碩士大同大學
光電工程研究所
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ABSTRACT In this thesis, we have simulated the distributions of optical field in ridge waveguides by BPM (Beam propagation method) to investigate the ridge waveguides that we designed have single mode characteristic. We have used the photolithography and the ICP-RIE (Inductively Coupled Plasma Reactive Ion Etching) dry etching technique to produce ridge waveguides on the SOI (Silicon on Insulator). Waveguide devices fabricated on SOI substrates have the facility of simple in design and easy to combine with semiconductor devices and integrated optical devices. The results show that the properties changed insensitively with respect to the etching depth. In order to increase the couple efficiency, the ridge waveguide end facets are polished by a series of diamond films to reduce the end facets roughness to 0.1µm without serious insertion loss. In addition, the alignment consideration between the single-mode fiber and ridge waveguide has also been studied by photolithography method to produce self-alignment U-groove. It can improve the performance of coupling single-mode fiber to the ridge channel waveguide and some experimental results have been illustrated in this thesis.
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"Silicon waveguides and methods to address their polarization sensitivity =: 以硅為基的光波導及其偏振敏度解決方案." 2003. http://library.cuhk.edu.hk/record=b5891700.
Full textAbstract:
Chan Po Shan.Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.
Includes bibliographical references (leaves 79).
Text in English; abstracts in English and Chinese.
Chan Po Shan.
Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Application of Optical Waveguides --- p.1
Chapter 1.2 --- Planar Waveguide Characterizations --- p.2
Chapter 1.3 --- Silicon-On-Insulator Rib Waveguides --- p.3
Chapter 1.4 --- Polarization compensation schemes --- p.4
Chapter 1.5 --- Objectives --- p.6
Chapter 2 --- Silicon-On-Insuiator Rib Waveguides --- p.9
Chapter 2.1 --- Properties of Silicon Waveguides --- p.9
Chapter 2.2 --- Single Mode Rib Waveguides Simulations --- p.11
Chapter 2.3 --- Special design optimisations --- p.14
Chapter 2.4 --- Fabrications and Results --- p.16
Chapter 3 --- Polarization Characteristics of SOI Rib Waveguides --- p.20
Chapter 3.1 --- Properties of silicon and effect of rib structure --- p.20
Chapter 3.2 --- Polarization affected by Form Birefringence --- p.21
Chapter 3.3 --- Case Study: Arrayed Waveguide Grating --- p.23
Chapter 3.4 --- Possibility of polarization Compensation in planar waveguides --- p.26
Chapter 4 --- Fixed Polarization Compensation Techniques --- p.30
Chapter 4.1 --- Theoretical analysis of slant rib waveguides on polarization --- p.30
Chapter 4.2 --- Focused Ion Beam Trimming of SOI waveguides --- p.31
Chapter 4.3 --- Possible applications --- p.36
Chapter 5 --- Tuneable Polarization Compensation Techniques --- p.41
Chapter 5.1 --- stress on rib waveguide for polarization compensation --- p.41
Chapter 5.2 --- Magnetostriction and Magnetostrictive Materials --- p.42
Chapter 5.3 --- Sputtering of soft magnetic layer on SOI rib waveguides --- p.46
Chapter 5.4 --- Test results and Analysis --- p.47
Chapter 6 --- Advanced SOI Devices --- p.55
Chapter 6.1 --- Unique planar optoelectronics devices --- p.55
Chapter 6.2 --- Simulation and Fabrications --- p.57
Chapter 6.3 --- Test Results and Discussion --- p.58
Chapter 7 --- Conclusion --- p.62
Chapter 7.1 --- Summary --- p.62
Chapter 7.2 --- Future work --- p.63
Appendices
Chapter A1 --- Effective Index Method --- p.66
Chapter A2 --- Beam Propagation Method --- p.70
Chapter A3 --- SOI Rib Waveguide Fabrication --- p.72
Chapter A4 --- Focused Ion Beam --- p.74
Chapter A5 --- Polarization Optics --- p.76
List of Publications --- p.79
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Mangal, Nivesh. "SOI Based Integrated-Optic Microring Resonators for Biomedical Sensing Applications." Thesis, 2012. http://hdl.handle.net/2005/3174.
Full textAbstract:
Integrated Silicon Photonics has emerged as a powerful platform in the last
two decades amongst high-bandwidth technologies, particularly since the adop-
tion of CMOS compatible silicon-on-insulator(SOI) substrates. Microring res-
onators are one of the fundamental blocks on a photonic integrated circuit chip o ering versatility in varied applications like sensing, optical bu ering, ltering, loss measurements, lasing, nonlinear e ects, understanding cavity optomechanics etc.
This thesis covers the design and modeling of microring resonators for biosensing applications. The two applications considered are : homogeneous biosensing and wrist pulse pressure monitoring. Also, the designs have been used to fabricate ring resonator device using three different techniques. The results obtained through characterization of these devices are presented. Following are the observations made in lieu of this:
1) Design modeling and analysis - The analysis of ring resonator requires the study of both the straight and bent waveguide sections. Both rib and
strip waveguide geometries have been considered for constructing the device as
a building block by computing their respective eigen modes for both quasi-TE
and quasi-TM polarizations. The non-uniform evanescent coupling between the straight and curved waveguide has been estimated using coupled mode theory. This method provided in estimating the quality-factor and free spec-
tral range (FSR) of the ring-resonator. A case for optimizing the waveguide gap in the directional coupler section of a ring resonator has been presented for homogeneous biosensing application. On similar lines, a model of applying ring resonator for arterial pulse-pressure measurement has been analyzed. The results have been obtained by employing FD-BPM and FDTD including semi-
vectorial eigen mode solutions to evaluate the spectral characteristics of ring
resonator. The modeling and analytical results are supported by commercial
software tools (RSoft).
2) Fabrication and Characterization - For the fabrication, we employ
the design of ring resonator of radius 20 m on SOI substrate with two different waveguide gaps of 350 and 700 nm. Three different process sows have been used for fabricating the same device. The rst technique involved using negative e-beam resist HSQ which after exposure becomes SiO2, acts as a mask for Reactive-Ion Etching (RIE); helping in eliminating an additional step. The second technique involved the use of positive e-beam resist, PMMA for device patterning followed by metal deposition with lift-o . The third tech-
nique employed was Focussed Ion-beam (FIB) which is resist-less patterning
by bombarding Ga+ ions directly onto the top surface of the wafer with the help of a GDS le.
The characterization process involved estimation of loss and observing the be-
havior of optical elds in the device around the wavelength of 1550 nm using
near-field scanning optical microscopy (NSOM) measurement. The estimation of roughness-induced losses has been made by performing Atomic Force Microscopy (AFM) measurements.
In summary, the thesis presents novel design and analysis of SOI based microring resonators for homogeneous biosensing and wrist pulse pressure sensing
applications. Also, the fabrication and characterization of 20 m radius ring-
resonator with 500 500 nm rib cross-section is presented. Hence, this study
brings forth several practical issues concerning application of ring resonators
to biosensing applications.
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Chi, Chun-ting, and 机峻廷. "Subwavelength structures for Silicon-On-Insulator waveguide Crossing." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/38643484832457465722.
Full textAbstract:
碩士國立中山大學
光電工程學系研究所
102
In this thesis, we try to design a low-loss, low- crosstalk and compact dimension waveguide crossing structure with subwavelength grating structures. 1.We discuss the theory and the application limits of subwavelength grating (SWG) structures. 2.Review SOI waveguide crossing designs and discuss the strengths and weakness . 3.Design waveguide crossing structure with subwavelength structures. 4.Discuss and analysis the results from 3D FDTD simulation. According to the simulation results, we can get a waveguide crossing structure with 0.13dB loss and crosstalk <-35dB. But the crossing dimension would be limited by the characteristics of SWGs, we need more than 20 period number to get efficient SWGs. The crossing dimension is 12 x 12 μm^2 of our design.
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Chuang, Chun-Yen, and 莊竣硯. "Silicon Photonics: The Grating Coupler between Optical Fiber and Silicon Waveguide on Silicon on Insulator." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/8rc992.
Full textAbstract:
碩士國立交通大學
光電工程研究所
102
As the time goes on, the generation for information is grown explosively. The need of high-speed transport is increasing for human. The computation power and the transports also grow exponentially to fulfill the need of the communication. However, the transport of the electronic integrated circuit meets the physical limitation for 10 GHz. This limits the improving of the transport speed. Here is a novo technology for solving these problems called silicon photonics. It integrates the photonics circuit and the electronics devices for multiplexing, photonics for communication and electronics circuit for computation. Compare to the copper, the photonics circuit provides the high-speed, low loss, and wide band channel for communication. This will push the improvement of the technology. The photonics circuit should contain the following components: the light source, low loss waveguide, high-speed modulators, the interface between fiber and the waveguide, the logic optical switch, and the photo detector. In this work, we will focus on the interface, diffraction grating coupler, between the optical fiber and the silicon waveguide. First, we will describe the theories of the grating. By applying the grating equation, we design the 1-D diffraction grating coupler as the interface. The simulation result is calculated the coupling efficiency for 40.34% at wavelength 1550 nm with 1 dB bandwidth 39 nm. Besides, we also fabricate the real device at Nano Device Laboratory (NDL) followed by the simulation model. We have successful fabricated the grating structure with the period 630 nm, 640 nm and 650 nm. The width of the grating trench is from 270 nm to 380 nm with 10 nm steps. The shallow etching for 80 to 110 nm is also completed. The coupling efficiency of the experiment result is 21.92% at wavelength 1572 with 1 dB bandwidth 23.4 nm. The experiment result is much lower than the simulation result, but we show the benchmarks which compare to the Ghent University. The number is acceptable. In the end, we fabricated the grating coupler on the real SOI wafer. Next step is reducing the error between the simulation results and the experiments. Furthermore, how to reach high efficiency and broadband grating coupler is the final goal in the future.
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Cheng, Hsin-yen, and 鄭欣彥. "Design and Fabrication of Silicon-on-Insulator Arrayed Waveguide Grating Device." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/26648103641594662850.
Full textAbstract:
碩士義守大學
機械與自動化工程學系碩士班
93
The traditional optical communication network system just transfers one wavelength on the fiber, while dense wavelength division multiplexing (DWDM) device allows multiple wavelengths to be carried on the same fiber. Using DWDM not only save the set-up optical fiber cost and time, but also increase the optical fiber capacity. Based on these priorities, DWDM devices have become one of the most important elements in optical communication network. The large demand for upgrading the numbers of channels and channel spacing in DWDM optical communication systems is increasing at a tremendous rate owing to the rapid spread of the internet and multimedia services. There are three different technologies to implement DWDM function, including Thin Film Filter (TFF), Array Waveguide Grating (AWG), and Fiber Bragg Grating (FBG). Due to higher technology priority, low cost, easy mass production, minimized size and easy integration, AWG provides a good choice and solution for DWDM optical communication systems. Arrayed waveguide gratings (called AWG’s or PHASAR’s) have become key components in modern wavelength dispersion multiplexing systems for their muiti-functional and muiti-application properties. Silicon-on-Insulator AWG (SOI-AWG) show excellent promise and can provide key practical devices in dense wavelength dispersion multiplexing (DWDM) systems. The behaviors of SOI- AWG device is depended on the manufacturing parameters and uniformity. The purpose of this study is to investigate the geometrical shape, detail scale, and material processes of the SOI- AWG design with insensitive polarization and low insertion loss performance. The theoretical simulation of AWG device was obtained from solving wave equations by Beam Propagation Method (BPM). Based on the simulation results, the devices will be fabricated by thin-film deposition, photolithography and dry-etching processes. The optical characteristics of amorphous-silicon (a-Si) film, and AWG device were measured by spectrophotometer. The topography of rib structure waveguides, a-Si film was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The structures of the a-Si film was identified by x-ray diffraction (XRD). X-ray Photoelectron Spectroscopy (XPS) was used to analyze the 卅卅-Si compositions. High resolution transmission electron microscopy (HRTEM/EDAX) was used to study the localized interface structure and compositional distribution of a-Si films. The transmission spectrum of AWG’s device indicated the insertion loss, between two channels of crosstalk, channel of side-lobe were -5dB, -25dB and -45dB respectively by 3D beam propagation method. The performance of AWG device transmission spectrum was determined by reasonable design and fabricating errors. The fabricating errors were unavoidable and gave great impacts on the device performance. The possible fabricating errors included the large refractive index variation of film, surface roughness of film and sidewall roughness of waveguide, and the errors of the etching dimension and shape.
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"Compact waveguide grating couplers for silicon photonic integrated circuits." Thesis, 2010. http://library.cuhk.edu.hk/record=b6075251.
Full textAbstract:
An apodized grating coupler with the best coupling efficiency hitherto reported for shallow-etched waveguide grating couplers is described. By appropriate choice of waveguide/grating thicknesses and varying the coupling strength of the grating coupler via tailoring its fill factor to optimize the mode matching, a coupling loss of only 1.2dB was obtained for each fiber/silicon waveguide interface with a slightly titled optical fiber.Photonic integrated circuits (PICs) based on Silicon-on-insulator (SOI) substrate were proposed to make miniaturized photonic devices on chip, so that low-cost and compact devices for applications including sensing, inter/intra-chip communications and optical fiber communications could be made. One of the key challenges in the development of highly integrated PICs is efficient coupling of light between a submicron-sized nanophotonic wire and an optical fiber due to the large loss inherent from the mismatch in mode field size between the optical fibers and the nanophotonic wire waveguides. An attractive approach for efficient coupling is to use diffractive grating couplers which show many advantages over alternative approaches. However the angled alignment of the optical fiber to the grating as reported in the previous work is not desirable for a low-cost optical packaging process.
The 2D grating couplers could be used as polarization splitter. Polarization insensitive coupling and polarization-diversity circuits are realized by the 2D grating couplers. We also demonstrated a novel silicon waveguide grating which serves dual functions: as a 1x2 variable integrated beam splitter/combiner and as an out-of plane diffractive element for coupling light. The split ratio can be tuned by changing the launch position of the optical fiber without introducing much excess loss. An integrated Mach-Zehnder interferometer (MZI) is implemented with this novel functional element. This MZI was demonstrated as a demodulator for differential phase-shift-keying (DPSK) signal.
We demonstrated a simple technique to realize vertical fiber coupling with linearly chirped grating periods. No additional fabrication process is required yet a comparable coupling efficiency is achieved with the proposed chirped grating couplers with vertical optical fibers. Design and experimental results of onedimensional (lD) gratings, two-dimensional (2D) gratings, focusing gratings and fully-etched nanoholes gratings are described in the thesis. We also describe the waveguides and grating couplers fabricated on silicon-on-sapphire for mid-infrared applications.
Chen, Xia.
Adviser: H.K. Tsang.
Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: .
Thesis (Ph.D.)--Chinese University of Hong Kong, 2010.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
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Tsai, Ming-Lung, and 蔡明倫. "Fabrication and Analysis of Microrings and Waveguide Coupling on Silicon-on-Insulator Substrate." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/16759794179218135146.
Full textAbstract:
碩士國立臺灣大學
電子工程學研究所
102
Based on our laboratory’s successful fabrication of microdisk resornators, we try to fabricate microring resornators and waveguide coupling structure on silicon-on-insulator substrate in this thesis. At the end, we have successfully fabricated such resornators and coupling structure with max quality factor 9600 from whispering gallery modes (WGM) in microring resornators. There are two problems encountered in our device fabrication .First, ICPRIE is usually used to fabricate SOI device during etching, while there is no Fluorine in our facility. Second, there are unwanted holes appearing due to under-exposure in the e-beam lithography. These two problems had been solved by referring to the literature and carrying out systematic tests. In coupling experiments, we got the FSR of a 10um microring is twice that of a 20um microring, so we can conclude that the coupling with waveguide and microring was successful and there are WGMs in microring resonators. The relation between quality factor and the microring diameter is also consistent to our expectations. Finally, for the application of our devices, we test temperature variation and optical excitation. We observed the redshift phenomenon by increasing the temperature and got the thermo-optic coefficient almost the same as those in the literature. In optical excitation by a green laser, we observed an unexpected phenomenon. Referring to the temperature-induced refractive index change and the carrier-induced refractive index change, we prove that only red shift will be observed under such optical excitation condition.
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Tseng, Sheng-chieh, and 曾聖傑. "Birefringence and Dispersion of Silicon-on-insulator Waveguide using Optical Low-coherence Interferometry." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/89672210644157282311.
Full textAbstract:
碩士國立臺灣科技大學
光電工程研究所
98
A silicon-on-insulator (SOI) platform with the big advantage of the mature complementary metal-oxide-semiconductor (CMOS) compatible processing has been well developed to be a highly integrated microphonics due to its large refractive-index difference between silicon and silicon dioxide layers. Currently, new modulation formats are being proposed to enhance the performance and spectral efficiency of optical communication systems in core, metro, and access networks. The formats are mainly the optical phase related technologies, which imply the importance of birefringence. However, the chromatic dispersion is another important factor for the signal distortion. In this thesis, the methodology to characterize the birefringence and chromatic dispersion on SOI waveguides will be experimentally demonstrated. Among a variety of birefringence characteristics, the optical low-coherence interferometer (OLCI) illustrates a higher resolution, 10-6, which is related to the device length and optical ruler generated by the high-coherence laser source. The birefringence of the SOI waveguides with the thickness of 5?慆, the width of 5?慆 and the etch depth of 2.5?慆 was demonstrated as 7.9x10-4. Another filtering type of array waveguide grating (AWG) was also taken for verification and shown as the similar birefringence of 4.7x10-4. Time of flight (TOF), modulation phase shift (MPS) and interferometric methods are three main approaches for chromatic dispersion measurement techniques. Compared with the most widely used commercial dispersion, TOF and MPS, the interferometric technique is a less expensive and effective approach. The SOI waveguides with the same geometrical dimensions in the birefringence testing was showing a high dispersion of around -900 ps/(nm km) from the balanced and unbalanced arms of the interferometer. We successfully utilized the interference techniques to demonstrate the birefringence and chromatic dispersion of 5?慆 thick SOI waveguides. Our final goal is to develop a reliable and precise characteristic tool to in-situ monitor the optical system performance.
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Chi-HanChang and 張智涵. "Investigation of π-phase-shifted Long-Period Waveguide Gratings on Silicon-on-Insulator (SOI) Substrates." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/ed64zt.
Full textAbstract:
碩士國立成功大學
微電子工程研究所
102
We propose a design of the long-period waveguide gratings (LPWGs) on silicon-on-insulator (SOI) substrates. In this work, SOI channel waveguides were defined and etched by ICP as core guiding layer. In addition, the cladding layer was realized by deposited TiO2 into the top surface of SOI film. The transmission spectra of these LPWGs were then measured with optical spectrum analyzer. The full-width at half-maximum(FWHM) is 9.2nm. The transmission dip contrast close to 17.3dB was observed at the wavelength of 1577nm. The phase-shifted long period gratings with a finite number (M) of sections cascaded together are proposed and fabricated. It is expected theoretically and to be later justified experimentally that an M-section phase-shifted long period grating would produce (M2) sidelobes between two dominant rejection bands, while the separation between the two rejection bands increases linearly with respect to M.
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Guo-ShianWang and 王國賢. "Long-Period Waveguide Gratings on Silicon-on-Insulator(SOI) Substrates Fabricated by Anisotropic Wet Etching." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/40092447045030721014.
Full textAbstract:
碩士國立成功大學
微電子工程研究所碩博士班
101
Long-period gratings (LPGs) are functioned based on the light coupling between the core guiding modes and the cladding modes at specific wavelengths (resonance wavelengths). However, the conventional FBG implemented on the optical fiber inevitably faces the geometry and material constraints associated with the fiber, which impose significant limitations on the device functionalities. To bypass the foregoing constraints, a long-period waveguide grating (LPG) employing a waveguide structure has been developed instead to provide an additional flexibility needed in designing various LPG-based devices. In general, the traditional long-period waveguide gratings were manufactured using low refractive index materials. In this thesis, high-refractive index silicon was used for the first time to explore its practicality for the long-period waveguide gratings fabrication. Specifically, the device was etched and patterned on SOI wafer via an anisotropic wet etching technique and eventually the long-period waveguide gratings were successfully fabricated with silicon ridge waveguide incorporated as an optical waveguide core layer. In addition, the cladding layer based on amorphous silicon with refractive index slightly lower than the crystalline silicon was deposited using plasma-enhanced chemical vapor deposition (PECVD) by judiciously controlling the flow rate of SiH4. With the amorphous silicon used as the cladding layer, the gratings with pitch as long as tens of micrometer could now be defined and patterned using the conventional photolithography. As mentioned previously, the wet etching was adopted to overcome the line width restriction entailed by the use of a much cheaper plastic mask; making the device feature size less than 20μm easily realizable, specifically, waveguides with a line width of 20, 18, 15, 12, 10 and 8μm had all been successfully fabricated to cut down the number of guided modes present in the core region. Additionally, a commercial software was used to design gratings with six different pitches needed, namely, Λ20=100μm, Λ18=107μm, Λ15=93μm, Λ12=95μm, Λ10=109μm and Λ8=91μm. The subsequent experimental results demonstrate that the LPWG devices appear to resonate within a wavelength range between 1563 and 1578nm, and the waveguide width of 8μm has delivered a dip contrast as high as 20 dB, while the device with the waveguide width of 10μm has its FWHM measured as narrow as 3.3nm. Then the experimental results with polarization controller inserted into the measurement setup show that the devices resonate within a wavelength range between 1563 and 1580nm, and the waveguide width of 8μm has delivered a dip contrast as high as 30 dB, while the device with the waveguide width of 12μm has its FWHM measured as narrow as 1.76nm with input light polarized as transverse electric (TE) wave. With transverse magnetic (TM) polarized wave provided as an input, the waveguide width of 10μm yields a dip contrast as high as 14.5 dB, while the device with the waveguide width of 10μm has its FWHM measured as narrow as 1.32nm.
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Zhang, Yang active 2013. "Multi-layer silicon photonic devices for on-chip optical interconnects." Thesis, 2013. http://hdl.handle.net/2152/23344.
Full textAbstract:
Large on-chip bandwidths required for high performance electronic chips will render optical components essential parts of future on-chip interconnects. Silicon photonics enables highly integrated photonic integrated circuit (PIC) using CMOS compatible process. In order to maximize the bandwidth density and design flexibility of PICs, vertical integration of electronic layers and photonics layers is strongly preferred. Comparing deposited silicon, single crystalline silicon offers low material absorption loss and high carrier mobility, which are ideal for multi-layer silicon PIC.
Three different methods to build multi-layer silicon PICs based on single crystalline silicon are demonstrated in this dissertation, including double-bonded silicon-on-insulator (SOI) wafers, transfer printed silicon nanomembranes, and adhesively bonded silicon nanomembranes. 1-to-12 waveguide fanouts using multimode interference (MMI) couplers were designed, fabricated and characterized on both double-bonded SOI and transfer printed silicon nanomembrane, and the results show comparable performance to similar devices fabricated on SOI. However, both of these two methods have their limitations in optical interconnects applications.
Large and defect-free silicon nanomembrane fabricated using adhesive bonding is identified as a promising solution to build multi-layer silicon PICs. A double-layer structure constituted of vertically integrated silicon nanomembranes was demonstrated. Subwavelength length based fiber-to-chip grating couplers were used to couple light into this new platform. Three basic building blocks of silicon photonics were designed, fabricated and characterized, including 1) inter-layer grating coupler based on subwavelength nanostructure, which has efficiency of 6.0 dB and 3 dB bandwidth of 41 nm, for light coupling between layers, 2) 1-to-32 H-tree optical distribution, which has excess loss of 2.2 dB, output uniformity of 0.72 dB and 3 dB bandwidth of 880 GHz, 3) waveguide crossing utilizing index-engineered MMI coupler, which has crossing loss of 0.019 dB, cross talk lower than -40 dB and wide transmission spectrum covering C-band and L-band.
The demonstrated integration method and silicon photonic devices can be integrated into the CMOS back-end process for clock distribution and global signaling.text
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Malathi, S. "Design And Analysis Of Integrated Optic Resonators For Biosensing Applications." Thesis, 2012. http://etd.iisc.ernet.in/handle/2005/2568.
Full textAbstract:
In this thesis, we have designed and optimized strip waveguide based micro-ring and micro-ring and micro-racetrack resonators for biosensing applications. Silicon-On-Insulator (SOI) platform which offers several advantages over other materials such as Lithium Niobate, Silica on Silicon and Silicon nitride is considered here. High index contrast enables us to miniaturize the biosensor devices and monolithic integration of source and detectors on the same chip. We have considered the dispersive nature of the waveguide and proceeded towards optimization.
Finite difference schemes and Finite Difference Time Domain (FDTD) methods are the primary tools used to model the biosensor. Various structures such as channel waveguides and beam structures are analyzed on the basis of their suitability for sensing applications. Strip and Rib waveguides are the two geometries considered in our studies.
In an optical guiding structure, effective index of the propagating optical mode can be induced by two different phenomena:
i. Homogeneous Sensing
In this category, effective index of a propagating optical mode changes with uniformly distributed analytes extending over a distance well exceeding the evanescent field penetration depth. The sample serves as the waveguide cover.
ii. Surface Sensing
In the case of surface sensing, analytes bound to the surface of the waveguide. The effective index of an optical mode changes with the refractive index as well as the thickness of an adlayer. A thin layer of adsorbed or bound molecules transported from liquid or gaseous medium serving as waveguide cover is referred as an adlayer. Both homogeneous and surface sensing schemes are addresses in this work.
By bulk sensing method, the characteristics of bioclad covering the device are studied. Optimization of the resonator structure involves the analysis of following parameters:
• Gap between the ring and bus waveguides
• Free spectral range
• Extinction ratio
• Quality factor
We have achieved a maximum bulk sensitivity of 115 nm / RIU with ring waveguide width of 450 nm and bus width of 350 nm which is better than an earlier reported value of
70 nm/ RIU.
We have proposed a novel detection scheme consisting of a micro-racetrack resonator formed over a cantilever structure. The devoice works on the principle of opto-mechanical coupling to detect conformational changes due to biomolecular adherence. BSA (Bovine Serum Albumin) and IgG ( Immuno Globulin G) are the two proteins considered in the work. Mechanical analysis of the beam for tensile and compressive stresses and corresponding spectral responses of the racetrack resonators are analyzed both by semi-analytical and method and numerical analyzes. We compared various aspects of rib and strip waveguide racetrack resonators. We have proved by numerical simulation, that the device is capable of distinguishing tensile and compressive stress. Two strip waveguides of dimensions : 450 nm X 220 nm and 400 nm X 180 nm, former supporting both Quasi-TE and Quasi-TM modes where as the second configuration allows only Quasi-TE mode alone. Sensitivity of the cantilever sensor is : 0.3196 x 10-3 nm/ µɛ at 1550 nm wavelength.