TE/TM-Pass Polarizer Based on Lithium Niobate on Insulator Ridge Waveguide

We propose a TE/TM-pass polarizer based on a shallow X-cut lithium niobate-on-insulator (LNOI) ridge waveguide. In shallow X-cut LNOI ridge waveguides, the leaky mode is interchanged between TE and TM polarization waves depending on the ridge waveguide height. The phenomenon does not occur in silicon-on-insulator ridge waveguides. We use this special loss mechanism for TE/TM-pass polarizers. We evaluate structural and wavelength dependencies of polarizers by a vectorial finite-element method. The extinction ratios of 108 dB/mm and 27 dB/mm are obtained for TE-pass and TM-pass polarizers.