Geometry Parameter Optimization of Large Cross-Sectional S-Shaped Bent Rib Waveguides for Silicon Based Optical Switches

By using a genetic algorithm, geometry parameters of large cross-sectional S-bend rib waveguides are optimized aiming at the least total loss when the propagation loss is considered. Optimized results are presented as an example of S-bend rib waveguides based on silicon-on-insulator (SOI) 4×4 optical switches. The value of 2dB/cm is given to the propagation loss according to the experimental results. The simulation results indicate that the total loss drops from 1.0002dB down to 0.4375dB without considering a lateral offset. If the offset is adopted, the total loss reduces from 0.5463dB to 0.2365dB. In addition, the effect of the rib height ratio on the loss is analysed, and the optimal ratio is obtained to be 0.55.