UC Santa Barbara

Photonic integrated circuits (PICs) play a major role in the advancement of optical networks. One of the constraints of PICs is the high propagation loss of optical waveguides. As the complexity in PICs increases, so does the power usage and heat generation; therefore, bringing “fiber-like” losses on-chip would not only allow for the improvement of chip performance, but it would also revolutionize delay line technologies allowing longer delay lines to be integrated on chip, otherwise not practically feasible. The design of such waveguides and optical circuits requires a balance of numerous tradeoffs between mode-size, bending radius, and footprint, to name a few. Herein, we present the design and fabrication of optical delay line circuits using an ultra-low loss waveguide platform, which utilizes a high aspect ratio buried Si3N4 core planar waveguide.

Optical delay line circuits are defined here as any optical circuit that requires the optical signal to be delay by a certain amount of time for its proper functionality. Such devices are used in many applications ranging from medical to sensing and national defense. In this dissertation we present the integration of three optical delay line circuits: Tunable true time delay for broadband phased array antennas application, a programmable dispersion compensation filter, and an optical gyroscope waveguide coil. The design tradeoff, fabrication, and results for each circuit are present and highlighted in detail.