CMOS-compatible and fabrication-tolerant MMI-based polarization beam splitter

A compact multimode interference (MMI) coupler based polarization beam splitter (PBS) is proposed and realized, which is fabrication-tolerant and fully compatible with standard silicon photonic foundry processes. The PBS on the 220 nm silicon strip waveguide is as small as 4.2 μm×132.64 μm. Besides, the simulated fabrication tolerances of the width, the length and the etching depth are more than 100 nm (80 nm), 5 μm (5.65 μm) and 60 nm (120 nm) for TE (TM) mode, respectively. In addition, the experimental results demonstrate that the bandwidth is about 26 nm with the extinction ratio better than 15 dB.