Inverse-Designed Ultra-Compact Polarization Demultiplexer

An ultracompact ($3 \times 3 \mu m^{2}$) silicon nitride-based $1 \times 2$ polarization demultiplexer for near-infrared (1400–1600nm) is designed by the inverse method. It achieves around 90% transmission, efficiently separating TE and TM polarization.