Modeling and analysis of optical switches based on directional couplers

This thesis concerns the simulation of optical switching in directional couplers. A new coupled mode theory for the analysis of tapered structures in directional coupler is presented and validated. The improvement over the recently developed non-orthogonal coupled mode theory using local modes for the tapered sections of a coupler (4) is demonstrated by an assessment with the finite-difference beam propagation method (FD-BPM). The improved coupled mode theory is found to be more accurate for tilt angels exceeding to 0.5...