Electronic Photonic Integrated Circuits and Control Systems

Photonic systems can operate at frequencies several orders of magnitude higher than electronics, whereas electronics offers extremely high density and easily built memories. Integrated photonic-electronic systems promise to combine advantage of both, leading to advantages in accuracy, reconfigurability and energy efficiency. This work concerns of hybrid and monolithic electronic-photonic system design. First, a high resolution voltage supply to control the thermooptic photonic chip for time-bin entanglement is described, in which the electronics system controller can be scaled with more number of power channels and the ability to daisy-chain the devices. Second, a system identification technique embedded with feedback control for wavelength stabilization and control model in silicon nitride photonic integrated circuits is proposed. Using the system, the wavelength in thermooptic device can be stabilized in dynamic environment. Third, the generation of more deterministic photon sources with temporal multiplexing established using field programmable gate arrays (FPGAs) as controller photonic device is demonstrated for the first time. The result shows an enhancement to the single photon output probability without introducing additional multi-photon noise. Fourth, multiple-input and multiple-output (MIMO) control of a silicon nitride thermooptic photonic circuits incorporating Mach Zehnder interferometers (MZIs) is demonstrated for the first time using a dual proportional integral reference tracking technique. The system exhibits improved performance in term of control accuracy by reducing wavelength peak drift due to internal and external disturbances. Finally, a monolithically integrated complementary metal oxide semiconductor (CMOS) nanophotonic segmented transmitter is characterized. With segmented design, the monolithic Mach Zehnder modulator (MZM) shows a low link sensitivity and low insertion loss with driver flexibility

Fabrication of superconducting nanowire single proton detectors

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 81-85).The future NASA Mars project will need an ultra-fast, highly sensitive photodetector to increase the bandwidth of free-space long-range communication, which is now done primarily using RF signals. Our original motivation in fabricating superconducting nanowire single-photon detectors (SN-SPD) is to fulfill this need. The SN-SPD's reported GHz counting rates [1] make it very attractive for this application. A new fabrication process for making SN-SPDs using hydrogen-silsesqioxane (HSQ), a high-resolution electron-beam lithography resist will be presented. An electron-beam proximity-effect correction program was developed to achieve nanowires with uniform linewidths, which is important for device performance. Finally, we present initial test results that show device functionality and performance. Our best device has a detection efficiency of [approx.] 10 % at 1064 nm photon wavelength at 2.1 K and a photon-induced voltage-pulse duration of [approx.] 3 ns.by Joel K. Yang.S.M

Quantum Optoelectronic Detection and Mixing in the Nanowire Superconducting Structure

The recent advancement of superconducting nano devices has allowed for making a Superconducting Nanowire Single Photon Detector (SNSPD), whose extraordinary features have strongly motivated the research community to exploit it in many practical applications. In this thesis, an experimental setup for testing the SNSPD has been established. It contains an in-house packaging that meets the requirements of RF/microwave and optoelectronic characterizations. The quantum efficiency and detection efficiency measurements have confirmed that our approach is satisfactory. The dark count performance has reached the anticipated level. The factors affecting rise and fall times of the photoresponses are addressed. Based on the successful setup, the characterizations including dc, small signal ac measurements have been undertaken. The measurements are aimed at quantitatively investigating Cooper pair density in the superconducting nanowire. The experimental method involves a two-step, small signal S-parameter measurement either in the presence or absence of optical powers. The subsequent measurements by varying the temperature and dc bias current have achieved remarkable understanding on the physical properties of SNSPD nanowires. Then, the electrically induced nonlinearity is studied via the large signal RF and Microwave measurements. The experiments are a set of one-tone and two-tone measurements, in which either the RF driving power is varied at a fixed frequency, or vice versa. Two major nonlinear microwave circuit analysis methods, i.e. time-domain transient and hybrid-domain harmonic balance analysis, are employed. The simulation result reveals the optimized conditions of reaching the desired nonlinearity. Finally, we have successfully measured the optoelectronic mixing products in an electrically pumped optoelectronic mixer, which has identical structures as that of the SNSPD. The experiments confirm that this mixer is not only sensitive to the classical light intensities, but also to that of the single photon level. Meanwhile, the quantum conversion matrices is derived to interpret the quantum optoelectronic mixing effects

Nonlinearity and Gating in Superconducting Nanowire Single Photon Detectors

The quantum properties of electromagnetic radiation at single photon level promise to offer what are classically inaccessible. Single photon sources and detectors are therefore on demand for exploiting these properties in practical applications, including but not limited to quantum information processing and communication. In this thesis, I advance Superconducting Nanowire Single Photon Detectors (SNSPD) both in terms of models describing their operation, and their performance. I report on characterization, semi-empirical modeling, quantum-optical modeling and detector tomography. The results provide more accurate methods and formulations to characterize and mathematically describe the detectors, valuable findings from both application and device points of views. I also introduce the concept of Gated SNSPDs, show how to implement and how to characterize them. Through series of theoretical and experimental investigations, I show performance advantages of Gated SNSPDs in terms of dead time and dark count rate, important figures for many applications like quantum key distribution. The ultimate limitations of gated operation are also explored by physical modeling and simulation steps

High Efficiency Silicon Photonic Interconnects

Silicon photonic has provided an opportunity to enhance future processor speed by replacing copper interconnects with an on chip optical network. Although photonics are supposed to be efficient in terms of power consumption, speed, and bandwidth, the existing silicon photonic technologies involve problems limiting their efficiency. Examples of limitations to efficiency are transmission loss, coupling loss, modulation speed limited by electro-optical effect, large amount of energy required for thermal control of devices, and the bandwidth limit of existing optical routers. The objective of this dissertation is to investigate novel materials and methods to enhance the efficiency of silicon photonic devices. The first part of this dissertation covers the background, theory and design of on chip optical interconnects, specifically silicon photonic interconnects. The second part describes the work done to build a 300mm silicon photonic library, including its process flow, comprised of basic elements like electro-optical modulators, germanium detectors, Wavelength Division Multiplexing (WDM) interconnects, and a high efficiency grating coupler. The third part shows the works done to increase the efficiency of silicon photonic modulators, unitizing the χ(3) nonlinear effect of silicon nanocrystals to make DC Kerr effect electro-optical modulator, combining silicon with lithium niobate to make χ(2) electro-optical modulators on silicon, and increasing the efficiency of thermal control by incorporating micro-oven structures in electro-optical modulators. The fourth part introduces work done on dynamic optical interconnects including a broadband optical router, single photon level adiabatic wavelength conversion, and optical signal delay. The final part summarizes the work and talks about future development

Ultra-high-resolution optical imaging for silicon integrated-circuit inspection

This thesis concerns the development of novel resolution-enhancing optical techniques for the purposes of non-destructive sub-surface semiconductor integrated-circuit (IC) inspection. This was achieved by utilising solid immersion lens (SIL) technology, polarisation-dependent imaging, pupil-function engineering and optical coherence tomography (OCT). A SIL-enhanced two-photon optical beam induced current (TOBIC) microscope was constructed for the acquisition of ultra-high-resolution two- and three-dimensional images of a silicon flip-chip using a 1.55μm modelocked Er:fibre laser. This technology provided diffraction-limited lateral and axial resolutions of 166nm and 100nm, respectively - an order of magnitude improvement over previous TOBIC imaging work. The ultra-high numerical aperture (NA) provided by SIL-imaging in silicon (NA=3.5) was used to show, for the first time, the presence of polarisation-dependent vectorialfield effects in an image. These effects were modelled using vector diffraction theory to confirm the increasing ellipticity of the focal-plane energy density distribution as the NA of the system approaches unity. An unprecedented resolution performance ranging from 240nm to ~100nm was obtained, depending of the state of polarisation used. The resolution-enhancing effects of pupil-function engineering were investigated and implemented into a nonlinear polarisation-dependent SIL-enhanced laser microscope to demonstrate a minimum resolution performance of 70nm in a silicon flip-chip. The performance of the annular apertures used in this work was modelled using vectorial diffraction theory to interpret the experimentally-obtained images. The development of an ultra-high-resolution high-dynamic-range OCT system is reported which utilised a broadband supercontinuum source and a balanced-detection scheme in a time-domain Michelson interferometer to achieve an axial resolution of 2.5μm (in air). The examination of silicon ICs demonstrated both a unique substrate profiling and novel inspection technology for circuit navigation and characterisation. In addition, the application of OCT to the investigation of artwork samples and contemporary banknotes is demonstrated for the purposes of art conservation and counterfeit prevention

On-Chip Integrated Functional Near Infra-Red Spectroscopy (fNIRS) Photoreceiver for Portable Brain Imaging

RÉSUMÉ L'imagerie cérébrale fonctionnelle utilisant la Spectroscopie Fonctionnelle Proche-Infrarouge (SFPI) propose un outil portatif et non invasif de surveillance de l'oxygénation du sang. SFPI est une technique de haute résolution temporelle non invasive, sûr, peu intrusive en temps réel et pour l'imagerie cérébrale à long terme. Il permet de détecter des signaux hémodynamiques à la fois rapides et neuronaux ou lents. Outre les avantages importants des systèmes SFPI, ils souffrent encore de quelques inconvénients, notamment d’une faible résolution spatiale, d’un bruit de niveau modérément élevé et d’une grande sensibilité au mouvement. Afin de surmonter les limites des systèmes actuellement disponibles de SFPI non-portables, dans cette thèse, nous en avons introduit une nouvelle de faible puissance, miniaturisée sur une puce photodétecteur frontal destinée à des systèmes de SFPI portables. Elle contient du silicium photodiode à avalanche (SiAPD), un amplificateur de transimpédance (TIA), et « Quench-Reset », circuits mis en oeuvre en utilisant les technologies CMOS standards pour fonctionner dans les deux modes : linéaire et Geiger. Ainsi, elle peut être appliquée pour les deux fNIRS : en onde continue (CW- SFPI) et pour des applications de comptage de photon unique. Plusieurs SiAPDs ont été mises en oeuvre dans de nouvelles structures et formes (rectangulaires, octogonales, double APDs, imbriquées, netted, quadratiques et hexadecagonal) en utilisant différentes techniques de prévention de la dégradation de bord prématurée. Les principales caractéristiques des SiAPDs sont validées et l'impact de chaque paramètre ainsi que les simulateurs de l'appareil (TCAD, COMSOL, etc) ont été étudiés sur la base de la simulation et de mesure des résultats. Proposées SiAPDs techniques d'exposition avec un gain de grande avalanche, tension faible ventilation et une grande efficacité de détection des photons dans plus de faibles taux de comptage sombres. Trois nouveaux produits à haut gain, bande passante (GBW) et à faible bruit TIA sont introduits basés sur le concept de gain distribué, d’amplificateur logarithmique et sur le rejet automatique du bruit pour être appliqué en mode de fonctionnement linéaire. Le TIA proposé offre une faible consommation, un gain de haute transimpédance, une bande passante ajustable et un très faible bruit d'entrée et de sortie. Le nouveau circuit mixte trempe-reset (MQC) et un MQC contrôlable (CMQC) frontaux offrent une faible puissance, une haute vitesse de comptage de photons avec un commandable de temps de hold-off et temps de réinitialiser. La première intégration sur puce de SiAPDs avec TIA et Photon circuit de comptage a été démontrée et montre une amélioration de l'efficacité de la photodétection, spécialement en ce qui concerne la sensibilité, la consommation d'énergie et le rapport signal sur bruit.----------ABSTRACT Optical brain imaging using functional near infra-red spectroscopy (fNIRS) offers a direct and noninvasive tool for monitoring of blood oxygenation. fNIRS is a noninvasive, safe, minimally intrusive, and high temporal-resolution technique for real-time and long-term brain imaging. It allows detecting both fast-neuronal and slow-hemodynamic signals. Besides the significant advantages of fNIRS systems, they still suffer from few drawbacks including low spatial- resolution, moderately high-level noise and high-sensitivity to movement. In order to overcome the limitations of currently available non-portable fNIRS systems, we have introduced a new low-power, miniaturized on-chip photodetector front-end intended for portable fNIRS systems. It includes silicon avalanche photodiode (SiAPD), Transimpedance amplifier (TIA), and Quench- Reset circuitry implemented using standard CMOS technologies to operate in both linear and Geiger modes. So it can be applied for both continuous-wave fNIRS (CW-fNIRS) and also single-photon counting applications. Several SiAPDs have been implemented in novel structures and shapes (Rectangular, Octagonal, Dual, Nested, Netted, Quadratic and Hexadecagonal) using different premature edge breakdown prevention techniques. The main characteristics of the SiAPDs are validated and the impact of each parameter and the device simulators (TCAD, COMSOL, etc.) have been studied based on the simulation and measurement results. Proposed techniques exhibit SiAPDs with high avalanche-gain (up to 119), low breakdown-voltage (around 12V) and high photon-detection efficiency (up to 72% in NIR region) in additional to a low dark- count rate (down to 30Hz at 1V excess bias voltage). Three new high gain-bandwidth product (GBW) and low-noise TIAs are introduced and implemented based on distributed-gain concept, logarithmic-amplification and automatic noise-rejection and have been applied in linear-mode of operation. The implemented TIAs offer a power-consumption around 0.4 mW, transimpedance gain of 169 dBΩ, and input-output current/voltage noises in fA/pV range accompanied with ability to tune the gain, bandwidth and power-consumption in a wide range. The implemented mixed quench-reset circuit (MQC) and controllable MQC (CMQC) front-ends offer a quenchtime of 10ns, a maximum power-consumption of 0.4 mW, with a controllable hold-off and resettimes. The on-chip integration of SiAPDs with TIA and photon-counting circuitries has been demonstrated showing improvement of the photodetection-efficiency, specially regarding to the sensitivity, power-consumption and signal-to-noise ratio (SNR) characteristics

High dimensional autocompensating quantum cryptography in optical fibers implemented with discrete and integrated photonic devices

O obxectivo global desta tese é contribuir ao deseño de novos sistemas de criptografía cuántica e ao desenvolvemento de dispositivos fotónicos discretos e integrados que implementen operacións específicas para implementalos usando multiplexación espacial. Deste xeito, na tese propoñense novos metodos de encriptación cuántica autocompensada, que fan uso dos modos espaciais propagados por diversas fibras ópticas (fibras de poucos modos e multinúcleo) para conseguir transmitir información en alta dimensión, correxindo tódalas fluctuacións que estes sofren ao longo da transmisión pola fibra. Ao mesmo tempo, deseñanse os distintos dispositivos fotónicos necesarios para implementar ditos métodos, baseados tanto en elementos ópticos discretos como en dispositivos integrados. En particular, na tese presentanse novos dispositivos para xerar estados cuánticos útiles en criptografía (baseados en estados vórtice), así como proxectores cuánticos capaces de medir ditos estados. Ademáis, na tese demóstrase a viabilidade de fabricar ditos dispositivos de xeito integrado por medio de intercambio iónico en vidrio