Silicon photonics: Coupling, propagation and modulation of light in silicon

Several technical challenges remain to be addressed for making silicon photonic chips a manufacturing commodity. These challenges include coupling light in and out of the photonic chip with minimum optical loss, propagating light in the silicon-on-insulator (SOI) waveguides with low scattering loss, as well as modulating light with a reliable actuation mechanism that is well understood. The objective of this thesis research is to develop a silicon photonic chip with integrated passive (e.g. routing) and active functions (e.g. modulation). To achieve the thesis objective, these technical challenges must be addressed.;The challenge of reducing coupling loss between the optical fibers and SOI waveguides can be addressed by using couplers or mode converters in combination with high quality optical facets. An etch-and-cleave method has been developed in this research to fabricate high quality facets with vertical sidewalls at the desired locations on the SOI wafers, in order to reduce coupling loss. The challenge of reducing propagation loss due to scattering in the SOI waveguides can be addressed by minimizing roughness at the waveguide sidewalls. A scattering loss measurement technique using integrated optical star couplers has been developed to allow efficient collection of loss data, and a robust low-loss SOI waveguide fabrication process has been demonstrated successfully. To accomplish modulation function in the silicon photonic chip, the thermo-optic effect and heat flow dynamics in silicon have been studied extensively using a finite-difference simulator. As a result of the simulation study, a set of design and optimization guidelines for SOI thermo-optic switches based on Mach-Zehnder Interferometer (MZI) configuration has been established, which can be a relevant and useful guide to optical switch designers.