Towards Large-Scale Integrated Electronic-Photonic Systems
Electrical and Electronics
Silicon is a well-known platform for the integration of mature electronic devices and systems. That has made the realization of very large and complex electronic circuitries feasible. Thanks to the advanced nanotechnology tools, the integration of photonic devices has also become possible and attracted attention for the past decade. However, there remain some challenges in integrated photonic systems including lack of fast, high performance, and mature electronic circuitries to control the photonic devices and perform fast, reliable, and efficient processing and measurement. Thanks to the silicon platform and new nanofabrication processes, mature electronic devices and novel photonic circuitries can be integrated on the same platform, offering new promising applications. The first part of the thesis is focused on the electronic-photonic co-design. In this part, typical challenges and limitations of laser phase and frequency stabilization systems have been discussed and two novel integrated electronic-photonic architectures have been co-designed, implemented, and successfully demonstrated to address those challenges. We demonstrated the first integrated Pound-Drever-Hall laser frequency stabilization system where all the electronic and photonic blocks (except the photodiode) have been integrated on a 180 nm CMOS SOI process, a commercially available CMOS node. The implemented PDH chip utilizes an electronically reconfigurable Mach-Zehnder interferometer (MZI) as an optical frequency reference to suppress the laser's frequency noise by more than 25 dB while occupying only 2.38 mm$^2$. The integrated PDH is orders of magnitude smaller and less sensitive to environmental variations compared to its bench-top scale counterparts. As another example, electronic and photonic chips were co-designed and hybrid integrated to make the first nanophotonic phase noise filter that is capable of suppressing the linewidth of a commercially available laser by more than a factor of 600. The performance of the hybrid-integrated nanophotonic phase noise, unlike its counterparts, is independent of the input light source and less-sensitive to some of the system parameters such as gain or delay mismatch. The second part of the thesis focuses on the concept of integrated optical phased arrays (OPAs). In this part, a new OPA architecture is proposed to address the challenges in the state-of-the-art. The new OPA is based on vertical phase shifters acting as nanophotonic waveguides as well. To realize the OPA with vertical phase shifters, extensive nanofabrication techniques have been utilized to pave the path towards the realization of large-scale optical phased arrays.