Nonlinear optical whispering gallery microresonators for photonics
Abstract
In this thesis, I have investigated the linear and nonlinear optical properties of whispering-gallery microdisk and microring resonators side coupled to an ordinary waveguide. A waveguide-coupled disk or ring resonator behaves much like a Gires-Tournois interferometer [1] which is simply a Fabry-Perot interferometer with a 100% reflecting back mirror. The configuration is simple and yet extremely interesting because, unlike a Fabry-Perot resonator which has two output ports, a Gires-Tournois interferometer restricts light to a single output port (reflection). For the waveguide-coupled microresonator, the equivalent reflection port is in the forward direction and no light is coupled into the backward direction. Thus, the device behaves as an "all-pass" or "phase-only" filter which only modifies the phase of light traversing it. The phase shift imparted is however, detuning-dependent and highly sensitive near resonance. In addition to this increased phase sensitivity, the light circulating inside the resonator is coherently built up to a higher intensity than that incident upon the resonator. The combined action of these two effects results in dramatically enhanced nonlinear phase-shifting properties. Additionally, the all-pass resonator exhibits strong group delay and group delay dispersion effects. The elegant simplicity of such a configuration allows it to serve as a building block for constructing compact integrated optical switches, optical logic devices, and engineerable waveguides for exotic-pulse modification. I have derived theoretical predictions for the construction of useful photonic devices and have outlined the physical limitations of their implementation. Finally, in order to test these predictions, I designed, fabricated, and tested several microresonator-based devices using nanofabrication technology.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 2003
- Bibcode:
- 2003PhDT........63H