High-Performance Polarization Splitter-Rotator Based on Lithium Niobate-on-Insulator Platform

We propose and experimentally demonstrate a high-performance polarization splitter-rotator based on the lithium niobate-on-insulator platform, consisting of an adiabatic taper, an asymmetric directional coupler, and a multimode interference mode splitter. Two injecting modes with orthogonal polarization states were separated, and the transverse magnetic (TM) polarization state was rotated to the transverse electric (TE) polarization state simultaneously. The designed device is fabricated in a single-step etching process, providing an extinction ratio of 20 dB over 80 nm wavelength range and insertion loss of less than 0.65 dB for both TE
₀
and TM
₀
modes launched. Lithium niobate-on-insulator, polarization splitter-rotator, extinction ratio.