UC Santa Barbara

Photonic integrated circuits are key building blocks for an ever-increasing range of applications, including optical communications, sensing, and position and navigation. A key challenge to today’s photonics integration is realizing circuits and functions that require low-loss waveguides on chip while balancing waveguide loss with device performance and footprint. The Si3N4 waveguide low-loss platform serves as a third platform that complements silicon photonics and III/V semiconductor-based photonics. Incorporating the low loss attributes of Si3N4 waveguides into a photonic circuit to realize varying functions requires tuning the properties of the waveguide through parameters like waveguide core geometry and upper cladding design. In this dissertation, the design, fabrication, and optimization of these waveguides and their applications are described, and several devices are demonstrated. The first device is a high-extinction tunable third-order resonator filter with record extinction ratio demonstrating an application that employs waveguide geometry for compact and higher FSR (free spectral range) devices. Next, delays and resonators for application to rotational sensing using low-loss, large-area designs are demonstrated. Lastly, a method for vertically integrating multiple waveguide layers, capable of integrating devices with different loss and footprint requirements, is demonstrated in the form of a multi-layer delay spiral.