Low Loss and Compact TE-Pass Polarizer on LNOI Platform with Subwavelength Grating Metamaterials

Polarization management is a key technique in integrated photonic circuits. In this paper, a low loss and compact TE-pass polarizer based on lithium niobate on insulator (LNOI) platform is presented. By utilizing subwavelength grating (SWG) metamaterials and inverse design algorithm, the TE0 mode propagates through the SWG region with minimal loss, while the TM0 mode is efficiently coupled out and suppressed through shape-optimized algorithm, thereby achieving an expanded bandwidth of the polarization extinction ratio (PER). With a footprint of 66 μm, the polarizer exhibits low insertion loss (IL) < 0.174 dB and a PER > 10 dB over 176 nm (1465–1641 nm), reaching 33.2 dB at 1550 nm. Furthermore, the proposed polarizer demonstrates superior overall performance, along with promising potential for polarization management and mode conversion in high-performance LNOI-based integrated photonic systems.