C-band four-channel CWDM (de-)multiplexers on a thin film lithium niobate–silicon rich nitride hybrid platform

A four-channel coarse wavelength division multiplexing (CWDM) (de)multiplexer on a thin film lithium niobate–silicon rich nitride hybrid platform has been designed, fabricated, and experimentally measured. Enabled by cascaded multimode waveguide Bragg gratings, the (de)multiplexer has a box-like spectral response, wide 1-dB bandwidth (10 nm), low excess loss ( < 1.08 d B ), and low channel cross talk ( < − 18 d B ). The central wavelengths of the (de-)multiplexer are 1531/1551/1571/1591 nm, which align to the wavelength grids stipulated by the standard ITU-T G.694.2.