Compact low-loss low-crosstalk echelle grating demultiplexer on silicon-on-insulator for CWDM

Abstract

This letter reports on the design of an ultra-compact echelle grating (EG) demultiplexer in O-band for Coarse wavelength division multiplexing (CWDM) systems based on silicon-on-insulator (SOI) and proposes an optimization idea. The correlation between optical performance and design parameters of EG device is analyzed based on the theory of Finite-difference time-domain (FDTD), providing a more accurate optimization reference. Further optimization is achieved by secondary adjustment of the blaze angle of grating facets and the position of output waveguides according to the simulated field distribution. The device has four channels with channel spacing of 20 nm and a small footprint of only 140×100 µm2. The simulated insertion loss for all channels is lower than 2 dB with insertion loss uniformity of below 1dB, and the crosstalk is better than 40 dB.