Investigation of polarization effects of microresonators

• Main Author: Jiang, Nian
• Other Authors: Shum Ping
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Electronic circuits
• Online Access: http://hdl.handle.net/10356/45619
• Institution: Nanyang Technological University

This final year report documents the simulations and experiments of investigating polarization effects of microresonator. Microresonator is made by microfiber/nanofiber, It includes a waveguide to channel light in a closed ring shape loop. This project mainly studied the polarization effects at the resonator’s coupling region in order to analyze the resonance phenomenon precisely. Two types of resonators, ring resonator and loop resonator were researched in this project. Simulations using Rsoft FULLWAVE were carried out as the first step of the investigation. It was found that the polarization properties of the twist resonators were mainly varied with the length of coupler. For twist resonator with coupling length 20µm to 35µm, self coupling transmission spectra overlapped with a minor shift of critical coupling wavelength. When the coupling length was around 150µm to 160µm, self coupling transmission spectra were clearly separated with splitting at the peak of the curve. For loop resonators, it showed well separated self coupling transmission spectrum without peak splitting. It was also noticed that the cross coupling transmission spectra for both loop and twist resonator were polarization insensitive. During the practical experiments, hand-made twist resonator was tested to support the simulation results. By carefully adjusting the resonator shape, slight self coupling transmission spectrum peak splitting was inspected for twist resonator with coupling length 160µm. This result coincided with simulation outcome. For resonator with 70µm coupling length, obvious resonance was inspected and it was noticed that critical coupling wavelength shifted for different polarization status. The phenomena observed during the experiment proved that the polarization properties of a microresonator were closely related to the coupler length.