Inverse Design of Ultra-Compact Polarizer for Integrated Silicon Photonics

The integrated waveguide polarizer is essential for photonic integrated circuits, and various designs of waveguide polarizers have been developed. As the demand for dense photonic integration increases rapidly, new strategies to minimize the device size are needed. In this paper, we have inversely designed an integrated transverse electric pass (TE-pass) polarizer with a footprint of 2.88 µm× 2.88 µm, which is the smallest footprint ever achieved. A direct binary search algorithm is used to inversely design the device for maximizing the transverse electric (TE) transmission while minimizing transverse magnetic (TM) transmission. Finally, the inverse-designed device provides an average insertion loss of 0.99 dB and an average extinction ratio of 33 dB over a wavelength range of 100 nm.