Quantum systems’ integration in chip-scale photonic circuits is the most promising way to succeed in scaling up complex systems for applications ranging from quantum computation to secure communications. Large systems with many components, especially for scaled all-optical quantum or classical processors, will require improved building blocks with greatly reduced loss, and enhanced bandwidth and robustness to fabrication uncertainties, temperature, etc. In this work, we introduce the concept of rapid adiabatic mode evolution that is the basis of a new family of passive devices with fundamentally improved performance, that we refer to as rapid adiabatic devices. In conventional adiabatic devices, a concept well known in photonics, the waveguide cross-section slowly evolves along the propagation direction, with no particular attention paid to transverse positioning of the cross-section. In contrast, in rapid adiabatic devices, we control the transverse position evolution (taking a tailored off-axis path while advancing along the direction of propagation). This has a major impact on the dominant crosstalk mechanism, the limiting factor to all performance metrics. By judicious synthesis and design, the dominant crosstalk coupling mechanism can be minimized or even set to zero everywhere along the structure. This concept brings a new paradigm to photonic passives that we stand the test of time as an important tool in the integrated photonics tool-box. We experimentally demonstrate a new integrated 2×2 beam splitter design we call a Rapid Adiabatic Coupler (RAC) in different fabrication platforms. The design is implemented in state-of-the art, field-leading CMOS photonics platforms pioneered in our group, taking into account foundry-imposed limitations on design. It nevertheless shows field-leading, very low-loss and extremely broadband 50:50 splitting ratio over hundreds of nanometers of optical bandwidth. In addition, we also demonstrate other photonic passives based on the concept – Rapid Adiabatic Crossings (RAX), a Rapid Adiabatic Mode Splitter (RAMS) as well as a Polarization Splitter Rotator based on the RAMS. These new high performance, compact components will enable larger-scale systems on chip with a higher number of components, not only for quantum photonics applications but also for other types of systems for sensing, optical AI accelerators, optical “FPGAs”, optical switches and routers, optical communication links and others. Another key building block for quantum photonic systems is integrated single photon sources. Following the first demonstration of a pair source integrated with pump filters by our group, here we demonstrate a monolithically integrated tunable photon pair source and pump filter on chip in a commercial, advanced 45nm CMOS microelectronics process. Next, we propose electronic-photonic quantum systems on chip, that contain monolithically integrated electronics and photonic components, as a platform to further scale up complexity in, and modularize, quantum systems on chip. As a first demonstration concept, we propose and demonstrate the first experimental step toward a “wall-plug” photon pair source implemented as an electronic-photonic monolithic chiplet. The idea is a CMOS die (or electronic-photonic block on the chip) that takes only electrical DC power, optical CW laser “DC power”, and control signals, and generates high quality photon pairs. The system contains a thermally tunable second-order filter with heater drivers integrated in the chiplet electronics to clean the input pump laser, a self-locking source ring with integrated electronic circuits that allow the ring resonance to automatically align to the pump laser and low-loss, high extinction, high-order thermally tunable filters. These results taken together show that monolithic integration in CMOS micro-electronics processes does allow high performance photonics, while also supporting scalable complex circuits with electronic control to account for the extreme sensitivity of photonic components and impart reconfigurability and tunability; showing it as a viable approach to build large-scale electronic-photonic systems with a realistic path to commercial technologies. This work was supported in part by the NSF RAISE-EQuIP program (Award 1842692) and by the Packard Foundation (Award 2012-38222). / 2023-05-23T00:00:00Z

Optical beamforming networks (OBFNs) are a strong contender for phased array operation, especially using microwave photonics (MWP), with advantages in size, weight, power efficiency and cost. Applications for such systems range from satellite to cellphone communication. The use of OBFNs require multiple components to up-convert, down-convert and process radio frequency (RF) signals in the optical domain. In this thesis, these components and a photonic packaging solution were designed and tested. For the OBFN itself, the modulation for up-conversion was performed with a micro-ring modulator, which was able to perform 1.11V forward bias modulation at 500MHz with a modulation depth of 21 dB. A true time delay optical ring resonator (ORR) was designed and characterized, yielding 784 ps delay at 3.33V heater bias, tunable to any value below this. An accessible, low-cost photonic packaging approach was developed, which achieved an optical coupling loss of 2.8 dB per facet. In conjunction with the photonic packaging was an electromagnetic interference (EMI) enclosure, which was able to block unwanted external RF signals. / Thesis / Master of Applied Science (MASc)

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Datacenter networks are not only larger but with new applications increasing the east-west traffic and the introduction of the spine leaf architecture there is an urgent need for high bandwidth, low cost, energy efficient interconnects. This paper will discuss the role integrated photonics can have in achieving datacenter requirements. We will review the state of the art and then focus on advances in optical switch fabrics and systems. The optical switch is of particular interest from the integration point of view. Current MEMS and LCOS commercial solutions are relatively large with relatively slow reconfiguration times limiting their use in packet based datacenter networks. This has driven the research and development of more highly integrated silicon photonic switch fabrics, including micro ring, Mach-Zehnder and MEMS device designs each with its own energy, bandwidth and scalability, challenges and trade-offs. Micro rings show promise for their small footprint, however they require an energy efficient means to maintain wavelength and thermal control. Latency requirements have been traditionally less stringent in datacenter networks compared to high performance computing applications, however with the increasing numbers of servers communicating within applications and the growing size of the warehouse datacenter, latency is becoming more critical. Although the transparent optical switch fabric itself has a minimal additional latency, we must also take account of any additional latency of the optically switched architecture. Proposed optically switched architectures will be reviewed.

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This thesis describes the fabrication of a set of bright, visible light-emitting silicon LEDs. These devices were fabricated in-house at the University of Saskatchewan using a custom plasma ion implantation tool, an annealing furnace, and a physical vapour deposition system. A high-fluence (F = 4 × 1015 cm^−2) implantation of molecular hydrogen ions extracted from an RF inductively coupled plasma at an energy of 5 keV was used to create a heavily damaged region in the silicon centered approximately 40 nm below the silicon surface with a width of approximately 56 nm. A matrix of annealing (e.g. thermal processing) processes at 400 ºC and 700 ºC and different durations (30 minutes and 2 hours) as well as an aluminum gettering procedure were tested with the goal of increasing the output electroluminescence intensity. Current-voltage characterization was used to extract information about the defect-rich nanocrystalline, light-emitting layer as well as the Schottky barrier height. This enabled comparison of these new devices with previous silicon LEDs based on porous silicon and other approaches. The processes which were used to fabricate these devices are compatible with standard CMOS processing techniques and could provide one solution to the problem of optical interconnect on multi-core chips. The scientific significance of this work is the demonstration of bright, visible light emission at mean photon energies ∼1.84 eV corresponding to a photon wavelength of λ ≈ 675 nm. This is remarkable given that ordinary crystalline silicon is an indirect bandgap material with a bandgap energy of 1.1 eV, in which band-to-band radiative recombination is forbidden by momentum conservation. The devices fabricated in this thesis have light emission properties similar to previous silicon LEDs based on nanocrystalline or nanoporous silicon. They have the advantage of being easily electrically driven. The nanocrystalline region which is the source of the light emission was nucleated from the ion-implanted layer below the surface of the silicon. This makes these devices mechanically robust and insensitive to environmental conditions. The engineering significance of this work is the production of CMOS compatible light emitters. This study demonstrated increased light emission efficiency at higher annealing temperatures which is likely due to enhanced diffusion and nucleation of silicon nanocrystals in the ion-implant damaged layer.

Over the last decade advances and innovations from Silicon Photonics technology were observed in the telecommunications and computing industries. This technology which employs Silicon as an optical medium, relies on current CMOS micro-electronics fabrication processes to enable medium scale integration of many nano-photonic devices to produce photonic integrated circuitry. However, other fields of research such as optical sensor processing can benefit from silicon photonics technology, specially in sensors where the physical measurement is wavelength encoded. In this research work, we present a design and application of a thermally tuned silicon photonic device as an optical sensor interrogator. The main device is a micro-ring resonator filter of 10 $\mu m$ of diameter. A photonic design toolkit was developed based on open source software from the research community. With those tools it was possible to estimate the resonance and spectral characteristics of the filter. From the obtained design parameters, a 7.8 x 3.8 mm optical chip was fabricated using standard micro-photonics techniques. In order to tune a ring resonance, Nichrome micro-heaters were fabricated on top of the device. Some fabricated devices were systematically characterized and their tuning response were determined. From measurements, a ring resonator with a free-spectral-range of 18.4 nm and with a bandwidth of 0.14 nm was obtained. Using just 5 mA it was possible to tune the device resonance up to 3 nm. In order to apply our device as a sensor interrogator in this research, a model of wavelength estimation using time interval between peaks measurement technique was developed and simulations were carried out to assess its performance. To test the technique, an experiment using a Fiber Bragg grating optical sensor was set, and estimations of the wavelength shift of this sensor due to axial strains yield an error within 22 pm compared to measurements from spectrum analyzer. Results from this study implies that signals from FBG sensors can be processed with good accuracy using a micro-ring device with the advantage of ts compact size, scalability and versatility. Additionally, the system also has additional applications such as processing optical wavelength shifts from integrated photonic sensors and to be able to track resonances from laser sources.

La photonique silicium est reconnue comme la technologie à même de répondre aux nouveaux défis des interconnexions optiques. Néanmoins, la photonique silicium doit faire face à d'importants défis. En effet, le Si ne peux pas émettre ou détecter de la lumière dans la plage de longueurs d'onde des télécom (1,3 µm à 1,5 µm). Par conséquent, les sources et les détecteurs sont mis en œuvre avec du Ge et des matériaux III-V. Cette approche multi-matériaux complique la fabrication des dispositifs et augmente le coût final du circuit. Cependant, les nanomatériaux ont été identifiés comme alternative pour la mise en œuvre d’émetteurs-récepteurs moins chers et plus petits.Cette thèse est dédiée à l'étude et au développement de dispositifs optiques et optoélectroniques sur la plateforme photonique silicium basés sur l’utilisation de nanotubes de carbone mono paroi (SWCNT). L’objectif principal est de démontrer les blocs fonctionnels de base qui ouvriront la voie à une nouvelle technologie photonique dans laquelle les propietés actives proviennent des nanotubes de carbone.Les nanotubes de carbone ont été étudiés comme matériaux pour la nanoélectronique avec la démonstration de transistors ultra-compacts à hautes performances. De plus, les SWCNTs semi-conducteurs (s-SWCNTs) sont également des matériaux très intéressants pour la photonique. Les s-SWCNTs présentent une bande interdite directe qui peut être ajustée dans la gamme de longueurs d'onde du proche infrarouge en choisissant le bon diamètre. Les s-SWCNT présentent une photoluminescence et une électroluminescence, pouvant être exploitées pour la mise en œuvre de sources de lumière. Ils présentent également diverses bandes d’absorption pour la réalisation de photodétecteurs. Ces propriétés font que les nanotubes de carbone sont des candidats très prometteurs pour le développement de dispositifs optoélectroniques pour la photonique.Le premier objectif de la thèse était l'optimisation des solutions de nanotubes de carbone. Une technique de tri par ultra-centrifugation assistée par polymère a été optimisée, donnant des solutions de haute pureté en s-SWCNT. Sur cette base, plusieurs solutions de s-SWCNTs ont été élaborées pour obtenir des SWCNTs émettant dans les longueurs d'onde comprise entre 1µm et 1,6µm.Le deuxième objectif était d’étudier l'interaction des s-SWCNT avec des guides d'onde silicium et des résonateurs optiques. Plusieurs géométries ont été étudiées dans le but de maximiser l'interaction des s-SWCNT avec le mode optique en exploitant la composante transverse du champ électrique. D'autre part, une approche alternative a été proposée et démontrée en utilisant la composante longitudinale du champ électrique. En utilisant la composante longitudinale, une amélioration de la photoluminescence, un seuil d’émission avec la puissance de pompe ainsi qu’un rétrécissement de la largeur spectrale des résonances dans les microdisques ont été observés. Ces résultats sont un premier pas très prometteur vers la démonstration d’un laser intégré à base de SWNTs.Le troisième objectif était d'étudier les dispositifs optoélectroniques à base de s-SWCNTs. Plus spécifiquement, une diode électroluminescente (DEL) et un photodétecteur ont été développés, permettant la démonstration du premier lien optoélectronique sur puce basé sur les s-SWCNT.Le dernier objectif de la thèse était d'explorer le potentiel de s-SWCNT pour l’optique non linéaire. Il a été démontré expérimentalement, qu’en choisissant la chiralité des s-SWCNTs, le signe du coefficient Kerr pouvait être soit positif ou négatif. Cette capacité unique ouvre un nouveau degré de liberté pour contrôler les effets non linéaires sur puce, permettant de compenser ou d'améliorer les effets non linéaires pour des applications variées. / Silicon photonics is widely recognized as an enabling technology for next generation optical interconnects. Nevertheless, silicon photonics has to address some important challenges. Si cannot provide efficient light emission or detection in telecommunication wavelength range (1.3μm-1.5μm). Thus sources and detectors are implemented with Ge and III-V compounds. This multi-material approach complicates device fabrication, offsetting the low-cost of Si photonics. Nanomaterials are a promising alternative route for the implementation of faster, cheaper, and smaller transceivers for datacom applications.This thesis is dedicated to the development of active silicon photonics devices based on single wall carbon nanotubes (SWCNTs). The main goal is to implement the basic building blocks that will pave the route towards a new Si photonics technology where all active devices are implemented with the same technological process based on a low-cost carbon-based material, i.e. SWCNT.Indeed, carbon nanotubes are an interesting solution for nanoelectronics, where they provide high-performance transistors. Semiconducting SWCNT exhibit a direct bandgap that can be tuned all along the near infrared wavelength range just by choosing the right tube diameter. s-SWCNTs provide room-temperature photo- and electro- luminescence and have been demonstrated to yield intrinsic gain, making them an appealing material for the implementation of sources. SWCNTs also present various absorption bands, allowing the realization of photodetectors.The first objective of this thesis was the optimization of the purity of s-SWCNT solutions. A polymer-sorting technique has been developed and optimized, yielding high-purity s-SWCNT solutions. Based on this technique, several solutions have been obtained yielding emission between 1µm and 1.6µm wavelengths.The second objective was the demonstration of efficient interaction of s-SWCNT with silicon photonics structures. Different geometries have been theoretically and experimentally studied, aiming at maximizing the interaction of s-SWCNT with optical modes, exploiting the electric field component transversal to light propagation. An alternative approach to maximize the interaction of s-SWCNT and the longitudinal electric field component of waveguide modes was proposed. Both, a power emission threshold and a linewidth narrowing were observed in several micro disk resonators. These results are a very promising first step to go towards the demonstration of an integrated laser based on CNTs.The third objective was to study optoelectronic SWCNT devices. More specifically, on-chip light emitting diode (LED) and photodetector have been developed, allowing the demonstration of the first optoelectronic link based on s-SWCNT. s-SWCNT-based LED and photodetector were integrated onto a silicon nitride waveguide connecting them and forming an optical link. First photodetectors exhibited a responsivity of 0.1 mA/W, while the complete link yielded photocurrents of 1 nA/V.The last objective of the thesis was to explore the nonlinear properties of s-SWCNT integrated on silicon nitride waveguides. Here, it has been experimentally shown, for the first time, that by choosing the proper s-SWCNT chirality, the sign of the nonlinear Kerr coefficient of hybrid waveguide can be positive or negative. This unique tuning capability opens a new degree of freedom to control nonlinear effects on chip, enabling to compensate or enhancing nonlinear effects for different applications.

Silicon photonics is nowadays a mature technology and is on the verge of becoming a blossoming industry. Silicon photonics has also been pursued as a platform for integrated nonlinear optics based on Raman and Kerr effects. In recent years, more futuristic directions have been pursued by various groups. For instance, the realm of silicon photonics has been expanded beyond the well-established near-infrared wavelengths and into the mid-infrared (3 - 5 µm). In this wavelength range, the omnipresent hurdle of nonlinear silicon photonics in the telecommunication band, i.e., nonlinear losses due to two-photon absorption, is inherently nonexistent. With the lack of efficient light-emission capability and second-order optical nonlinearity in silicon, heterogeneous integration with other material systems has been another direction pursued. Finally, several approaches have been proposed and demonstrated to address the energy efficiency of silicon photonic devices in the near-infrared wavelength range. In this dissertation, theoretical and experimental works are conducted to extend applications of integrated photonics into mid-infrared wavelengths based on silicon, demonstrate heterogeneous integration of tantalum pentoxide and lithium niobate photonics on silicon substrates, and study two-photon photovoltaic effect in gallium arsenide and plasmonic-enhanced structures. Specifically, performance and noise properties of nonlinear silicon photonic devices, such as Raman lasers and optical parametric amplifiers, based on novel and reliable waveguide technologies are studied. Both near-infrared and mid-infrared nonlinear silicon devices have been studied for comparison. Novel tantalum-pentoxide- and lithium-niobate-on-silicon platforms are developed for compact microring resonators and Mach-Zehnder modulators. Third- and second-harmonic generations are theoretical studied based on these two platforms, respectively. Also, the two-photon photovoltaic effect is studied in gallium arsenide waveguides for the first time. The effect, which was first demonstrated in silicon, is the nonlinear equivalent of the photovoltaic effect of solar cells and offers a viable solution for achieving energy-efficient photonic devices. The measured power efficiency achieved in gallium arsenide is higher than that in silicon and even higher efficiency is theoretically predicted with optimized designs. Finally, plasmonic-enhanced photovoltaic power converters, based on the two-photon photovoltaic effect in silicon using subwavelength apertures in metallic films, are proposed and theoretically studied.