Polarization Beam Splitter for Silicon-based Cross-slot Waveguides Using an Asymmetrical Evanescent Coupling System

摘要

A compact and broadband polarization beam splitter (PBS) for the silicon-based cross-slot waveguides (CSWs) is proposed by utilizing a cascaded asymmetrical evanescent coupling system composed of two CSWs and a horizontal slot waveguide (HSW) between them. By optimizing the width of the HSW, an asymmetrical directional coupler which can efficiently separate the TE and TM modes is constructed. Numerical results show that a short PBS of ～17.4μm with an insertion loss of 0.16 (0.37) dB, extinction ratio (ER) of 29.5 (24.2) dB for TM (TE) mode is achieved at 1.55 μm, and its bandwidth can be enlarged to ～90 nm for ER > 18 dB (TE).