Compact optical mode and polarization filtering devices based on subwavelength gratings on a lithium niobate on insulator platform

Abstract

We propose and demonstrate compact optical mode and polarization filtering devices on a lithium niobate on insulator (LNOI) platform. The subwavelength grating-based high-order mode pass filter and TM-pass polarizer are designed and experimentally demonstrated successfully. The measured insertion losses and extinction ratio at 1550 nm are lower than 1.9 dB and larger than 30 dB, respectively, while the device lengths are only about 50 μm.