UC Santa Barbara

Growing demands in high data capacity and low energy consumption have driven the development of high-performance optical interconnects for many commercial applications, such as links for long-haul, intra-/inter-datacenter, and 5G communication. Typically, the photonic devices used in these environments are optimized for operation at or above room temperature, however there is an existing and growing need for optimized photonic devices to operate in cryogenic and/or high-radiation environments. Applications of these optical interconnects range from control and readout from superconducting integrated circuits for quantum computing, to readout of tracking detectors in high-energy physics (HEP) particle accelerators, to readout of next-generation infrared (IR) focal plane array (FPA) detectors. Key to the success of these optical interconnects is the high-performance and ruggedization of the electro-optic modulator (EOM), typically implemented either as a remoted external device or as a directly modulated light source. This PhD dissertation addresses the challenges of optical interconnects for harsh environments in the following manner: (1) a novel and wavelength division multiplexed (WDM) scalable optical interconnect architecture has been developed—whereby the remoted EOM has been implemented as a microring resonator—and reduces both system complexity and energy consumption, (2) a high-speed optical link operating at cryogenic temperatures has been demonstrated—utilizing a silicon photonic based EOM—in addition to laser wavelength locking of the microring resonator, and (3) a semiconductor physics based model of the EOM has been developed to address the temperature dependent effects of the silicon p-n junction embedded in the microring resonator—based on the free-carrier plasma dispersion effect in doped silicon—to aid in the device design and optical interconnect link optimization for various harsh environment applications. Lastly, an outlook and suggested areas for future research—in the area of optimized silicon photonic devices for harsh environments—is given.