A compact SOI polarization beam splitter based on multimode interference coupler

Abstract

A multimode interference (MMI) polarization splitter with easy fabrication process was demonstrated in Silicon-On-Insulator substrate. The minimum device size, 8 µm×1034 µm was designed by Quasistate imaging effect theory. Numerical simulations show that this optimized MMI polarization splitter has a good fabrication tolerance. The tolerance of width and length is ±0.04 µm and ± 10 µm for transverse electric (TE) mode and ±0.14 µm and ±35 µm for transverse magnetic (TM) mode. The bandwidths are 20 nm and 80 nm for TE and TM respectively. Experiment results exhibits a -15 dB polarization extinction ratio bandwidth of 20 nm for the through-path and much wider for the cross-path. The extinction ratio and crosstalk achieve (−27.3 dB, −22.6 dB) for TE and (−26.6 dB, −23.9 dB) for TM.