Ultra-broadband TM-pass polarizer based on anisotropic metamaterials in lithium niobate on an insulator
Xu Han, Rui Cheng, Liang Huang, Panpan Yu, Lan‐Tian Feng, Guanghui Ren, Arnan Mitchell, Yonghui Tian, Xi‐Feng Ren, Haojie Xia
Abstract
An ultra-broadband TM-pass polarizer is designed, fabricated, and experimentally demonstrated based on subwavelength grating (SWG) metamaterials in a lithium niobate on an insulator (LNOI) platform. According to our simulation, the designed device is predicted to work at a 220 nm wavelength range from 1460 to 1680 nm, covering the S-, C-, L-, U-bands of optical fiber communication. By depositing and subsequently etching a silicon nitride thin film atop the LNOI chip, the SWG structures are formed successfully by using complementary metal-oxide semiconductor (CMOS)-compatible fabrication processes. The measured results show a high polarization extinction ratio larger than 20 dB and a relatively low insertion loss below 2.5 dB over a 130 nm wavelength range from 1500 to 1630 nm, mainly limited by the operation bandwidth of our laser source.