Thermally Stable External Cavity Laser Based on Silicon Nitride Periodic Nanostructures

In this paper we demonstrate a thermally stable silicon nitride external cavity (SiN EC) laser based on a 250 μm sized Reflective Semiconductor Optical Amplifier (RSOA) butt-coupled to a series of Si3N4 Bragg gratings acting as wavelength selective reflectors. The laser shows power outputs over 3 mW, a very low lasing threshold of 12 mA and with a typical Side-Mode Suppression Ratio of 45 dB. In this configuration a mode-hop free lasing regime over a range of 47 mA has been achieved (from 15 mA to 62 mA). Thermal stability of the lasing wavelength at temperatures up to 80°C is demonstrated. Further on, experimental results on a passive chip based on new 1D photonic crystal cavities are shown to have higher Q-Factors. This paves the way to avoiding thermal wavelength drifts and unlocks the possibility for these devices to be integrated in Dense WDM and optical-interconnect technologies, where transceivers must operate over a wide temperature range without active cooling.