Popovic, Milos A.Gevorgyan, Hayk2022-01-282022https://hdl.handle.net/2144/43712Emerging at the turn of the century as a promising optical integrated circuit technology, then purely of interest in academic research, silicon photonics (SiP) has been rapidly commercialized in recent years, with major semiconductor chip manufacturers, such as Intel, IBM, GlobalFoundries, and TSMC, offering SiP processes and many companies offering products based on this technology, currently creating a market value that reaches a significant fraction of the semiconductor industry. Akin to the progression of complementary metal-oxide-semiconductor (CMOS) transistors that followed the trend of Moore's Law, continuously scaling up the energy efficiency of integrated optical devices and making them more compact are of utmost importance for meeting the demands of next-generation photonic and electronic-photonic systems. Electro-optic (EO) modulators, as one of the main building blocks of these systems, have a wide range of applications in data communications, microwave photonic links, signal processing, analog-to-digital conversion, millimeter-wave sensing, quantum information processing, etc. In this work, we propose, study and demonstrate a number of novel electro-optic signal transducers and modulators based on electrically active silicon optical resonators that incorporate new optical and electrical design geometries and new materials to show energy efficiencies compatible with next-generation multiwavelength data communication systems as well as with emerging applications such as satellite-based millimeter-wave sensing and cryogenic-to-room temperature optical interconnects. Electro-optically modulated compound resonator ["photonic molecule" (PM)] devices consisting of coupled optical and electrical resonant cavities are proposed and demonstrated as RF-to-optical signal transducers. Based on them, we also introduce the new concept of frequency translating add/drop filters -- a fundamentally new category of filters that extends filters from linear, time-invariant to time varying systems. Owing to the strong interaction between RF and optical fields in micrometer-scale cavities and their multi-resonant nature, these devices offer improved conversion efficiencies compared to previously studied device architectures and could enable energy-efficient microwave photonic links, on-chip optical wavelength converters, isolators and frequency axis beam splitters for quantum photonics. Microring resonator modulators offering record sensitivity and non-thermal tuning in the O-band telecommunication window are demonstrated in CMOS electro-photonic monolithic processes. The first device is based on the "spoked-ring'' cavity, here equipped with vertical pn junction diode phase shifter, which improves the modulator sensitivity ten times compared to the earlier designs of this kind with interleaved lateral junctions. The second modulator is the smallest silicon microring modulator to date with 1.5um radius and record-large free-spectral-range (FSR). The device is based on a metal-oxide-semiconductor capacitor (MOSCAP) phase shifter with a few-nanometers-thick gate oxide and offers a sensitivity as high as that of the first device. It is the first MOSCAP resonant modulator demonstrated in a monolithic CMOS process. These modulators allow low-energy modulation, non-thermal channel tuning that consumes near zero static power, and an increased number of wavelength channels. These are essential attributes of microring modulators needed for next-generation, massively-parallel multiwavelength data links. We also developed silicon photonic modulators for applications in cryogenic-to-room-temperature optical data egress links. As part of this effort, operation of a silicon microring modulator and an electronic-photonic transmitter (amplifier+modulator) in a CMOS monolithic chip are demonstrated at 4K cryogenic temperature for the first time for transmitting low-voltage signals (down to 4mV) from 4K to the room-temperature environment. Additionally, we developed CMOS-organic hybrid microring modulators that use organic materials with large electro-optic coefficient, incorporated into the CMOS chip devices in a post-foundry processing stage. These devices take advantage of the low loss of silicon waveguides and the strong EO effect of the organic material, and could become a higher-efficiency alternative to regular silicon modulators. They could be used for transmitting low-voltage signals without requiring the integrated CMOS preamplification stage. These technologies are intended to become solutions for low-energy interconnection between superconducting logic and room-temperature CMOS memory and enable a new generation of low-power-consuming high-performance electronics, possibly scalable to full supercomputers, based on superconducting electronics.en-USElectrical engineeringThesis/Dissertation2022-01-260000-0003-0332-9736