Processing of high bandwidth signals with photonic integrated circuits

The modern world has witnessed a rapid upsurge in the demand for high data rate Transmission to support the contemporary technologies and numerous applications such as high-speed global networking, Internet of Things (IoT), etc. across multiple domains including artificial intelligence, machine learning, and cloud services. This demand is expected to only grow exponentially in the coming years, easing the advance of sixth-generation (6G) communications and beyond. Nevertheless, using the electrical domain to process such high-bandwidth Signals would be challenging owing to its shortcomings like restricted bandwidth, latency problems, high power consumption, cost, and complexity, and vulnerability to electromagnetic interference (EMI). Using silicon photonics, it is possible to implement optical signal processing which offers a wider bandwidth, relatively simpler implementation, increased flexibility, low latency and immunity to EMI and environmental radiation. Moreover, with the silicon-on-insulator (SOI) platform in integrated silicon photonics, it is possible to make use of the popular complementary metal oxide semiconductor (CMOS) technology. Optical communication has improved massively as a result of the combination of electronics and photonics on the silicon photonics platform. However, the thermal conductance of the chip constituents leads to thermal crosstalk which reduces the system performance, especially in densely-packed photonic integrated circuits. This thesis delves into the three fundamental aspects of high-bandwidth signal processing using photonic integrated circuits (PICs), namely, the generation of Nyquist pulse sequences, direct detection (DD) based orthogonal sampling, and thermal crosstalk alleviation. It Begins with the generation of sinc-shaped Nyquist pulse sequences with optical frequency combs (OFCs) using Mach-Zehnder modulators. Analysis of practical impairments like comb ripple, unwanted sidebands, and optical filter roll off in the process of sinc-shaped Nyquist pulse sequence synthesis is carried out for three-line, five-line, and nine-line OFCs. This is followed by the performance evaluation of a DD based orthogonal sampling system under the presence of non-idealities and comparison with the conventional DD system with electronic analog to digital converters. Finally, the thesis explains the issue of thermal crosstalk and provides mitigation techniques to minimize the same in PICs. All in all, this thesis lays a comprehensive and practical groundwork for developing thermally efficient, scalable, and metrologically precise photonic systems capable of performing high bandwidth signal processing. Deutsche Version Die moderne Welt erlebt einen rasanten Anstieg der Nachfrage nach Hochgeschwindigkeitsübertragungen zur Unterstützung moderner Technologien und zahlreicher Anwendungen wie globaler Hochgeschwindigkeitsnetzwerke, dem Internet der Dinge (IoT) und anderen in verschiedenen Bereichen, darunter künstliche Intelligenz, maschinelles Lernen und Cloud-Dienste. Es wird erwartet, dass dieser Bedarf in den kommenden Jahren exponentiell wächst und die Entwicklung der sechsten Mobilfunkgeneration (6G) und darüber hinaus vorantreibt. Die Nutzung des elektrischen Bereichs zur Verarbeitung solch breitbandiger Signale wäre jedoch aufgrund von Nachteilen wie eingeschränkter Bandbreite, Latenzproblemen, hohem Stromverbrauch, hohen Kosten, Komplexität und Anfälligkeit für elektromagnetische Störungen (Electromagnetic Interference - EMI) eine Herausforderung. Mithilfe der Siliziumphotonik ist die optische Signalverarbeitung realisierbar. Diese bietet eine größere Bandbreite, eine vergleichsweise einfache Implementierung, erhöhte Flexibilität, geringe Latenzzeiten und Unempfindlichkeit gegenüber elektromagnetischen Störungen und Umwelteinstrahlung. Darüber hinaus ermöglicht die SOI-Plattform (Silicon-on-Insulator) in der integrierten Siliziumphotonik die Nutzung der gängigen CMOS-Technologie (Complementary Meta…