Uniformly spaced λ/4-shifted Bragg grating array with wafer-scale CMOS-compatible process

We report on an integrated λ/4-shifted Bragg grating array using a wafer-scale complementary metal-oxide semiconductor (CMOS) compatible process with silicon-nitride waveguides. A sidewall grating was used to simplify the fabrication process, and a sampled Bragg grating with equivalent phase-shift structure was employed to achieve an accurate λ/4 phase shift. A four-channel λ/4-shifted Bragg grating array with highly uniform channel spacing was demonstrated with a measured channel spacing variation below 10 pm (1.25 GHz). The high channel-spacing uniformity and the CMOS-compatibility of the demonstrated device hold promise for integrated distributed feedback laser arrays for various silicon photonic applications.