Polarization Beam Splitter Based on MMI Coupler With SWG Birefringence Engineering on SOI

TLDR: In this paper, a novel polarization beam splitter (PBS) based on a subwavelength grating (SWG) multimode interference coupler for the silicon-on-insulator platform is presented.

Abstract: We demonstrate a novel polarization beam splitter (PBS) based on a subwavelength grating (SWG) multimode interference (MMI) coupler for the silicon-on-insulator platform The birefringence of the MMI coupler is engineered using SWG, which leads to a compact design footprint, with a device length of less than $100~\mu \text{m}$ Our PBS has simulated extinction ratios (ERs) better than 20 dB for both polarizations over the wavelength range from 1530 to 1625 nm that covers the entire $C$ - and $L$ -bands The fabricated device achieves the measured ERs larger than 20 dB at the wavelength of 1550 nm for both polarizations, and the insertion losses of 19 and 25 dB for the transverse electric (TE) and transverse magnetic (TM) polarizations, respectively, at 1550 nm In addition, the measured ERs are larger than 145 dB for the TE polarization and 117 dB for the TM polarization over an 84-nm spectral range covering the entire $C$ -band