No description available.

No description available.

Silicon photonics is leading the advent of very-large-scale photonic integrated circuits (PICs) in which lasers, modulators, photodetectors, and multiplexers are integrated on a single chip and synchronized to enable faster data transfer both between and within highly integrated chips. Silicon photonics now extends beyond communication applications, paving new paths for many emerging applications and holding great potential in creating a compact beam projector. Compact beam steering in the visible and near-infrared spectral range is required for emerging applications such as augmented reality (AR) and virtual reality (VR) displays, optical traps for quantum information processing, biosensing, light detection and ranging (LiDAR), and free-space optical communications (FSO). Here we discuss two novel integrated beam steering platforms in the visible and near-infrared wavelengths, optical phased array (OPA) and focal plane switch array (FPSA), that can shape and steer a light beam. Previous OPA demonstrations have been mainly limited to the near-infrared spectral range due to the fabrication and material challenges imposed by the smaller wavelengths. Here we present the first active blue light phased array at the wavelength of 488 nm, leveraging a high confinement silicon nitride (Si₃N₄) platform. We randomly and sparsely place the emitters to remove grating lobes, alleviate fabrication constraints at this short wavelength and achieve a wide-angle 1D beam steering over a 50° field of view (FoV) with a full width at half maximum (FWHM) beam size of 0.17°. This demonstration is a crucial first step in realizing a non-mechanical fully-integrated beam steering device for many emerging applications. Unlike 1D steering OPA, designing 2D OPA impose a different challenge. Numerous issues arise, including complicated waveguide routing and optical crosstalk between channels. Also, creating a highly directional beam without ghost images is required to deploy visible OPAs in emerging applications. However, current demonstrations of visible OPAs, including our first demonstration, suffer from the issue of low directionality due to the presence of grating lobes, high background noise and a low percentage of power in the main beam. We demonstrate an integrated OPA that generates a highly directional beam at blue wavelengths (488 nm) by leveraging a disordered hyperuniform distribution of emitters. This exotic distribution is found in birds’ cone photoreceptor arrangements, the most uniform sampling given intrinsic packing constraints. Such unique distribution allows us to mitigate fabrication and waveguide routing constraints and achieve a beam with low background noise, high percentage of power and no grating lobes. Large-scale integration of the platform enables fully reconfigurable high-efficiency light projection across the entire visible spectrum. The novel platform offers a viable platform for next-generation applications in visible-spectrum addressing, imaging, and scanning displays. Although OPA is an invaluable device for creating a highly directional beam on a chip-scale, OPA has an inherent power consumption issue. Its architecture requires simultaneous control of all the phase shifters in the system for operation. We propose a novel silicon photonics FPSA system for beam steering with orders of magnitude lower electrical power consumption than other state-of-the-art platforms. The demonstrated system operates in the near-infrared wavelength regime; however, this can be extended into different wavelengths. Our demonstration enables low-size, weight, and power (SWaP) LiDAR for precision and autonomous robotics and optical scanners for mobile devices.

<p>Lab-on-a-chip technologies have created a burgeoning number of new and novel devices designed to automate biological processes on-chip in an efficient and inexpensive format for far reaching point-of-care (POC) medicine and diagnostic treatments and for remote and on-line monitoring functions. This work designed a device that integrated advanced optical functionality on-chip with the microfluidics to relieve the reliance on traditional bulky and expensive free-space optics and a high-quality light source. The multimodal input beam was reshaped into an optimized geometry in the microchannel via a 2D system of lenses - improving the quality and reliability of detection through uniform detection of particles. A uniform beam geometry across the sample stream with a uniform beam width will allow repeatable excitation and burst duration to allow for more reliable and predictable detection. Numerous beam geometries were created and the quality and illumination properties confirmed by testing each with a couple sizes of fluorescent and non-fluorescent microspheres to test the effect of beam geometry and particle size combination on device performance. The measured coefficient of variation (CV) for fluorescent beads was found to have a particular beam geometry that yielded best device performance based on the bead size. Fluorescent beads 2.5µm in diameter had a CV of 8.5% for a 3.6 µm beam waist while 6 µm beads yielded a 14.6% CV with a 10 µm beam waist. When measuring scatter and fluorescence signal from a 10 µm the 2.5- and 6.0 µm beads gave 11.4% and 15.8% and 15.9% and 20.4% fluorescent and scatter CVs for each set of beads, respectively. Separately testing each beam geometry with 1-, 2-, and 5 µm beads did not yield any predictable ideal beam-bead ideal pairing for best performance. Lastly, further integration of optical function was shown through the on-chip collection of signals; CVs of 29% and 30% were measured for side scatter and forward scatter, respectively, for 5 µm beads. The reliability of this all-optically guided scheme was confirmed by comparing it to a simultaneously recorded free-space collection scheme. The coincidence rate was found to be 94% and 96% for the side scatter and forward scatter schemes. Both had very low false positive rates – below 0.5% - with missed detection rates that were satisfactory but in need of improvement. Sources of noise and device improvements were identified and suggested.</p> / Doctor of Philosophy (PhD)

This research introduces tellurium oxide (TeO2) glass doped with optically active erbium ions (Er3+) as an active oxide cladding material for silicon-on-insulator (SOI) waveguides for realization of a silicon-based erbium-doped waveguide amplifier (EDWA) for integrated optics. Optical amplification of this nature is enabled by energy transitions, such as stimulated absorption and emission, within the shielded 4f shell of the rare-earth atomic structure caused by excitation from photons incident on the system. Er3+ ions are doped into the TeO2 film during deposition onto the SOI waveguides using a reactive magnetron co-sputtering system operated by McMaster’s Centre for Emerging Device Technologies (CEDT). Prior to fabrication, the waveguides are designed using photonic CAD software packages, for optimization of the modal behaviour in the device, and Matlab, for characterization of the optical gain performance through numerical analysis of the rate and propagation equations of the Er3+-based energy system. Post fabrication, the waveguide loss and gain of the coated devices are experimentally measured. The fabricated waveguide amplifier produces a peak signal enhancement of 3.84 dB at 1533 nm wavelength for a 1.7 cm-long waveguide device. High measured waveguide losses (> 10 dB/cm) produce a negative internal net gain per unit length. However, the demonstration and implementation of an active rare-earth doped cladding material on a silicon waveguide is successful, which is a major step in developing integrated optical amplifiers for conventional silicon photonics platforms. / Thesis / Master of Applied Science (MASc)

Microwave Photonics(MWP) has been defined as the study of photonic devices which operate at microwave frequencies and also their applications to microwave and optical systems. One or more electrical signals at microwave frequencies are transported over the optic link ,with electrical to optical and optical to electrical conversion on the transmission and receiving side respectively. The key advantages of microwave photonic links over conventional electrical transmission systems such as coaxial cables or waveguides ,includes reduced size, weight and cost, immunity to electromagnetic interference ,low dispersion and high data transfer capacity. Integrated Optics is the name given to a new generation of opto-electronic systems in which the familiar wires and cables are replaced by light-waveguiding optical fibers, and conventional integrated circuits are replaced by optical integrated circuits (OICs).Microwave Photonics with photonic integration can add the benefits of reduction in system size, losses, short path lengths leading to more efficient cost effective systems. In this thesis, a new approach for using 1-D linear arrays of curved waveguides as delay lines is presented. We propose a design for a passive phase shifter obtained by curved waveguide delay lines. The modulated RF signal obtains the phase shift in the optical domain which is transferred to the RF signal by heterodyning techniques .This phase shift is independent of the RF frequency and hence the Beam squinting which occurs in the conventional RF phase shifter systems is avoided in the proposed system. Switching between different lengths of the bent/curved waveguides can produce variable phase shifts ranging from 0 to 2 radians. The use of curved waveguides for delay generation and optimization of various parameters are the main topics of the research problem. The need for delay line is large and most of these were implemented previously using long optical fiber cables. More precise delays could be obtained by using waveguide delay lines as compared to fiber delay lines. Waveguides paves way for design in smaller dimensions ranging from m to nm in integrated optics. The differential phase shift for a signal propagating in a waveguide from waveguide theory is given as which clearly indicates that the differential phase shifts could be obtained in accordance with differential path lengths Δl with β as the propagation constant. S-bend waveguide sections of different lengths along with straight waveguide as reference for each section are employed. The phase delay is passively obtained by a differential path length change, where various phase shift values can be obtained by switching between different differential path lengths. Since the optical phase delay generated is in- dependent of the input RF frequency. A shift in the RF frequency, at the input will not change the phase or beam pointing angle when the phase shifter is employed for beam pointing in case of Phased Array Antenna applications. A 1-bit phase shifter is the firrst step in the design which could be further extended to n-bit phase shifter. Here 1-bit or n-bit ,is one where n can take any integer value. Each bit is composed of a reference phase signal pathway and a delayed phase signal pathway. When the optical signal goes every single bit through the reference phase the phase shift is ‘0’ radians ,the other is through the delayed path which is . For every n-bit, 2n delays can be obtained. For the 1-bit,2 delays are obtained. Switching between the path lengths is done using the directional coupler switches. Th optimization of different parameters of the S-bend waveguide delay line has been realized and studied. The design and optimisation of a 1-bit optical RF phase shifter is discussed which could be extended to n-bit phase shifters. These S-bends are studied analytically. Beam Propagation Method (BPM)is employed for modeling and simulation of the proposed device. An interferometric configuration is considered for practical measurement of optical phase. In this configuration the phase change is translated into amplitude or intensity measurement. One of the arms of the Maczehdner Interferometer has no path length change while the other arm has an S-bend structure which provides the path length difference as compared to the reference path, and hence produces the necessary phase shift at the output of the interferometer as required. By changing the path length difference between the two arms of the interferometer ,a change in intensity is produced at the output of the interferometer. In this study, integrated optic curved waveguide delay line phase shifters are designed and analyzed, considering the Titanium Di used Lithium Niobate Technology. This is because it has good electro-optic properties necessary for designing switches used for switching between delay segments. Practical parameters that can be fabricated are employed in the design and simulation studies reported here. Fabrication is also done using the Lithium Niobate Technology. However the fabrication studies are excluded from the main stream, as further fabrication studies are necessary to realise the actual devices de- signed. The fabrication aspects are left as scope for further development. The fabricated devices are shown as appendix to the thesis. Organisation of the thesis Chapter 1 gives the introduction to the fields of Microwave Photonics and Integrated optics and its applications. Chapter 2discusses the curved waveguide theory and design with coverage of materials and methods employed in the proposed system. Chapter 3 discusses the different types of delay lines and the design of the 1-bit phase shifter which can be extended to the design of a n-bit phase shifter with both analytical and simulation results. Chapter 4 discusses the method of phase measurement for the n-bit phase shifter and the possible applications where the phase shifter could be employed. Chapter 5 discusses conclusions and future work in the proposed area of work. Appendix A discusses the loss calculations for the Cosine S-bend waveguide. Appendix B gives the fabrication details. The references form the end part of the thesis.

No description available.

Today's information and communication industry is confronted with a serious bottleneck due to the prohibitive energy consumption and limited transmission bandwidth of electrical interconnects. Silicon photonics offers an alternative by transferring data optically and thereby eliminating the restriction of electrical interconnects over distance and bandwidth. Due to the inherent advantage of using the same material as that used for the electronic circuitry, silicon photonics also promises high volume and low cost production plus the possibility of integration with electronics. In this thesis, I introduce an all-silicon optical interconnect architecture that promises very high integration density along with very low energy consumption. The basic building block of this architecture is a vertically coupled photonic crystal cavity-waveguide system. This vertically coupled system acts as a highly wavelength selective filter. By suitably designing the waveguide and the cavity, at resonance wavelength of the cavity, large drop in transmission can be achieved. By locally modulating the material index of the cavity electrically, the resonance wavelength of the cavity can be tuned to achieve modulation in the transmission of the waveguide. The detection scheme also utilizes the same vertically coupled system. By creating crystal defects in silicon in the cavity region, wavelength selective photodetection can be achieved. This unique vertical coupling scheme also allows us to cascade multiple modulators and detectors coupled to a single waveguide, thus offering huge channel scalability and design and fabrication simplicity. During this project, I have implemented this vertical coupling scheme to demonstrate modulation with extremely low operating energy (0.6 fJ/bit). Furthermore, I have demonstrated cascadeability and multichannel operation by using a comb laser as the source that simultaneously drives five channels. For photodetection, I have realized one of the smallest wavelength selective detector with responsivity of 0.108 A/W at 10 V reverse bias with a dark current of 9.4 nA. By cascading such detectors I have also demonstrated a two-channel demultiplexer.

In this paper, the performance simulations of a novel ultra-compact balanced coherent photodetector for operation at a wavelength of 1.5 mu m are presented and design proposals for future fabrication processes are provided. It consists of a compact 2x2 MMI that is evanescently coupled into a germanium MSM photodetection layer. The simulations demonstrate dark current less than 10 nA, capacitance less than 20 fF, and optical bandwidth in the 10-30 GHz range. We propose utilizing the simplicity of direct wafer bonding to bond the detection layer to the output waveguides to avoid complicated epitaxial growth issues. This ultra-compact device shows promise as a high-speed, low-cost integrated silicon photonics solution for the telecommunications infrastructure.

Le développement de capteurs pour la détection de molécules présentes en très faible concentration est un enjeu sociétal et économique. Il permet de répondre à des besoins de mesure d’analytes dans les secteurs de la santé, de la défense ou encore de l’environnement. Les capteurs optiques intégrés possèdent plusieurs avantages permettant de répondre à ces problématiques. Dans cette thèse, des capteurs optiques intégrés à base de deux micro-résonateurs sont développés. Ils fonctionnent dans le domaine du proche infrarouge et permettent de détecter des molécules d’intérêt présentes en très faible quantité dans un échantillon biologique. Dans un premier temps, les critères de performances comme la sensibilité ou la limite de détection de micro-résonateurs seuls sont définis et optimisés. Puis, l’intérêt de transducteurs à base de deux micro-résonateurs cascadés ou insérés dans une structure interférométrique de type Mach-Zehnder permettant d’utiliser l’effet Vernier est mis en avant. Un algorigramme permettant d’optimiser la conception des transducteurs à effet Vernier est mis en place. Son efficacité est démontrée par la fabrication d’un transducteur à effet Vernier en matériaux polymères qui possède des performances dans l’état de l’art. Ensuite, des transducteurs en matériau silicium poreux sont étudiés. Ce matériau poreux permet d’augmenter la sensibilité du capteur en facilitant le greffage des analytes dans la structure. Les guides en silicium poreux pour la réalisation de micro-résonateurs simples sont optimisés théoriquement. L’avantage de l’utilisation conjointe de guides en polymères et en silicium poreux couplés sur la même puce intégrée, qui permet à la fois de réduire les pertes de propagation optique et d’augmenter la sensibilité du transducteur, ainsi qualifié d’hybride, est détaillé dans ce manuscrit. Les performances en sensibilité et limite de détection de transducteurs à effet Vernier hybride fabriqués à l’aide de guides en silicium poreux et en polymères sont étudiées théoriquement afin de prédire les performances de ces dispositifs. Enfin la mise en œuvre et les premiers essais de fabrication de transducteurs hybrides avec des guides en polymères et en silicium poreux sont détaillés. / The development of biosensors for the detection of extremely low concentration analytes is an economic and societal challenge. It ensures the needs to detect analytes in the economic fields of healthcare, defense and environment. Integrated optical sensors have several advantages to address these challenges. In this thesis, near infrared integrated biosensors for detection of low concentration molecules in biological samples are developed. They are based on two integrated micro-resonators transducers. Firstly, performances criterions such as sensitivity and limit of detection are defined and optimized for single micro-resonator biosensors. The advantage of micro-resonator transducers based on the Vernier effect are presented. To do so, a flowchart is developed in order to optimize the design of Vernier effect integrated transducers based on cascaded micro-resonators or micro-resonators positioned in a Mach-Zehnder interferometric structure. The efficiency of the design procedure is tested by the fabrication of a polymer transducer based on the Vernier effect with state of the art performances. Then, transducers based on porous silicon material are studied. This porous material eases the penetration and the grafting of the analytes in the sensor. Porous silicon waveguides are theoretically optimized for the fabrication of single micro-resonators. The interest of the implementation of polymer and porous silicon waveguides coupled on the same integrated chip, in order to reduce optical propagation losses and to increase sensor sensitivity, is demonstrated. The performances in sensitivity and limit of detection of hybrid porous silicon and polymer waveguides Vernier effect transducers are theoretically studied in order to estimate the performances of these integrated biosensors. Eventually, the design and the first fabrication trials of hybrid porous silicon and polymer waveguides transducers are presented.