Efficient and accurate synthesis of complex Bragg grating waveguide in dispersive silicon structures

Abstract

The complex Bragg-grating waveguide (CBGW) is a semiconductor strip channel with many side corrugations or teeth. The layer-peeling (LP) and layer-adding (LA) algorithms have shown that the CBGW can be designed to offer an arbitrary pre-selected spectral-transmission profile having multiple peaks, but such a structure generally requires a huge number of teeth and a long length scale. In this paper, we propose a modified LP/LA algorithm that can significantly reduce CBGW structure length and develop accompanying time/memory-saving simulation procedures. Dispersion engineering is also introduced to significantly improve the accuracy of the LP/LA algorithm for high-index-contrast structures. A CBGW for a transmission spectrum with three passbands is designed and optimized on the silicon-on-insulator platform. Results show that our design can shorten the length of the CBGW by 10 times compared to the original design by the LP algorithm. Compared to the original LP/LA algorithm, the modified algorithm with dispersion engineering significantly improves the matching between the reconstructed transmission and the actual spectrum obtained by simulation.