Low kappa, narrow bandwidth Si(3)N(4) Bragg gratings.

We investigate three approaches to low perturbation gratings to achieve lower linewidths in filters and semiconductor lasers. The three designs, which are labeled post, sampled, and high order, are DUV lithography compatible and were fabricated on 90 nm thick Si(3)N(4) strip waveguides. Reflection and transmission spectra measurements show coupling constant, kappa, values ranging from 0.23 cm(‑1) to 1.2 cm(‑1) with FWHM values of 74 pm to 116 pm. We discuss the tradeoffs between these geometries in terms of lowest linewidth, apodization, and curved waveguide layout. These results enable long cavity single mode lasers with kHz level linewidths on a monolithic platform.