Planar concave grating demultiplexer with distributed Bragg reflection facets

Abstract—We present measurement results of an ultracompact four-channel silicon-on-insulator planar concave grating demulti-plexer fabricated in a complimentary metal–oxide–semiconductor line using deep-ultraviolet lithography. The demultiplexer has four output channels separated by 20 nm and a footprint of only 280 m 150 m. The crosstalk is better than 25 dB and the on-chip loss is drastically reduced down to 1.9 dB by replacing each facet by a second-order Bragg reflector. Index Terms—Demultiplexing, diffraction, distributed Bragg re-flector (DBR), grating, silicon-on-insulator (SOI). I