Design and optimization of microphotonic integrated devices for communications applications

Abstract

The communication bottleneck that currently limits the efficiency of chip-to-chip and intra-chip data transfer could be eliminated if the electrical interconnects of the electronic chips inside computing devices could be replaced by photonics that can be interrogated by electronic means. In fact, in this Information Age where the digital data is expanding at an exponential rate, the synergy between integrated photonics and integrated electronics — known as integrated optoelectronics — is poised to be the most feasible approach to meet the information demand. However, whether such approach can be fully implemented would depend on the rate of progress of integrated photonics as the diversity and complexity of photonic devices are larger than those of electronic devices currently supporting our digital world. Investigation into some of the basic component devices of integrated photonics, with emphasis on efficient telecommunication applications, is the main thrust of this thesis.

In this thesis, we report on the optimization and new design proposals of microphotonic integrated component devices based on silicon-on-insulator (SOI) waveguides and traveling wave microresonators (TWMRs). The results are split into two parts. For part one of the thesis, attention was first given to the single-mode and polarization independent conditions at the telecommunication wavelengths for submicron SOI waveguides and microring resonators. The photonic-bandgap engineering of coupled-TWMRs through the use of periodic and aperiodc order were then looked into. Subsequently, we investigated the temperature effects of Raman scattering in submicron SOI waveguide for enhanced telecommunication applications. In part two of the thesis, the theme is on fast and slow light effects in either a single traveling wave micoresonator (TWMR) or a system of twin-coupled TWMRs. The main research objective here is on the use of degeneracy lifting of the cavity via the excitation of contra-propagating cavity modes to improve the fast and slow light effects in the TWMR-based circuits. Four different schemes to generate contra-propagating cavity modes in the TWMRs — the coupler-induced localized backscattering, the intracavity distributed backscattering that is assisted by the use of dual inputs, the intracavity distributed backscattering in a system of twin-coupled TWMRs that has only one resonator coupled to the bus waveguide and finally the contra-propagating cavity modes that is established due to the evanescent coupling of both the resonators to the bus waveguide in the twin-coupled TWMRs system that has negligible intracavity distributed backscattering — have been looked into for the enhancement of fast and slow light effects in the TWMRs.