A compact two-dimensional grating coupler used as a polarization splitter

TLDR

We demonstrate a novel polarization splitter based on a two‑dimensional grating etched in a silicon‑on‑insulator waveguide. The device couples orthogonal modes from a single‑mode optical fiber into identical modes of two planar ridge waveguides, is very compact, and couples light only to transverse‑electric modes of the planar waveguides. The extinction ratio exceeds 18 dB over 1530–1560 nm and the coupling efficiency is about 20 %, enabling use in a polarization‑diversity configuration for polarization‑insensitive photonic integrated circuits based on photonic crystal waveguides.

Abstract

We demonstrate a novel polarization splitter based on a two-dimensional grating etched in a silicon-on-insulator waveguide. The device couples orthogonal modes from a single-mode optical fiber into identical modes of two planar ridge waveguides. The extinction ratio is better than 18 dB in the wavelength range of 1530-1560 nm and the coupling efficiency is approximately 20%. The device is very compact and couples light only to transverse-electric modes of the planar waveguides. Therefore, it may be used in a polarization diversity configuration to implement a polarization insensitive photonic integrated circuit based on photonic crystal waveguides.