| This thesis develops a simple optimal design guideline for vertically coupled directional coupler filters, and reports on an experimental implementation of our design. The measured bandwidth of an InGaAsP/InP directional coupler filter fabricated at Bell-Northern Research is 8A at central wavelength 1.2655-;We simulate the effects of fabrication imperfections on the central wavelength and bandwidth. As a result, tunable directional coupler filters are proposed and designed to compensate the performance drift due to such fabrication imperfections. (Abstract shortened by UMI.).;During the course of the theoretical analysis, we uncover some of the flaws and mistakes in literature on coupled-mode theory and models, and develop a more general model for the optical power, as well as the electric field distributions in two-dimensional optical directional couplers. In addition, we also clear up the confusion in the analytic expressions of the bandwidth of directional coupler filters. |
