Silicon nitride Bragg grating with Joule thermal tuning for external cavity lasers

The letter presents a fabrication platform based on silicon nitride embedded in silica on silicon wafers. Long Bragg gratings have been fabricated for narrow linewidth lasers. A narrow stop-band (0.2 nm) Bragg grating with etched facet chips is achieved in this platform. Heaters have been integrated on the chips allowing tuning of the Bragg wavelength over 1.5 nm. Lasers have been obtained and tested by butt-coupling of one of these Bragg gratings to a reflective semiconductor optical amplifier (R-SOA). On these laser cavities, we obtained a continuous tuning range of 0.16 nm and a discontinuous tuning range of 1.5 nm.