Demonstration of Distributed Etched Diffraction Grating Demultiplexer

The design principles and measurement results for a compact shallow etched distributed diffraction grating waveguide demultiplexer are presented. The deeply etched diffraction grating facets are replaced with a shallow etched odd-order quarter wavelength Bragg reflector to increase the Fresnel reflection coefficient. A prototype device was designed for coarse wavelength demultiplexing applications and was fabricated in nanophotonic silicon-on-insulator platform using deep ultraviolet (DUV) optical lithography. The demultiplexer, which supports four channels with 20-nm channel spacing, shows a crosstalk of -25 dB.