TE-pass polarizer with high polarization extinction ratio based on thin-film lithium niobate

A compact on-chip polarizer with a high polarization extinction ratio is proposed and experimentally demonstrated on thin-film lithium niobate (TFLN). The device consists of a dual-taper structure and a dual-side asymmetric directional coupler (ADC) to enable efficient polarization separation. Experimental results show an average insertion loss below 0.5 dB over the wavelength range from 1500 to 1600 nm, while a polarization extinction ratio (PER) exceeding 20 dB is maintained across 1505-1575 nm, reaching a maximum of 43 dB at 1550 nm. With a compact footprint of only 193 µm and full compatibility with standard TFLN fabrication processes, the proposed polarizer provides an effective approach for polarization management in integrated photonic circuits.