High-performance and ultra-wide bandwidth silicon TM polarizer with suppressed reflection utilizing a tailored contra-mode conversion Bragg grating

We present a compact TM polarizer with high polarization extinction ratio (PER), low loss, and suppressed reflection over an ultra-wide bandwidth on a 220 nm silicon-on-insulator (SOI) platform. The device utilizes a contra-mode conversion Bragg grating (CMC-BG) with strong polarization dependence embedded in a multimode waveguide. Through a sophisticated grating design incorporating tailored chirping and apodization profiles to match modal properties, we have achieved, by simulation, a compact device footprint of 34.72 × 1.22 µm² and an ultra-wide bandwidth of 346 nm with PER > 40 dB and an insertion loss (IL) < 1 dB, a 5-fold increase over our previous design. Particularly notable is the polarizer's ability to suppress reflection to <-15 dB across an extended bandwidth exceeding 450 nm. Experimental measurements confirm the excellent performance of the fabricated TM polarizer, with IL < 1.2 dB (0.5 dB) and PER > 30 dB over a bandwidth of 336 nm (268 nm).