Narrow-linewidth, tunable external cavity dual-band diode lasers through InP/GaAs-Si3N4 hybrid integration

platform. Silicon nitride photonic integrated circuits, instead of silicon waveguides that suffer from high optical loss near 1 µm, are chosen to build a tunable external cavity for both InP and GaAs gain chips at the same time. Single frequency lasing at 1.55 µm and 1 µm is simultaneously obtained on a single chip with spectral linewidths of 18-kHz and 70-kHz, a side mode suppression ratio of 52 dB and 46 dB, and tuning range of 46 nm and 38 nm, respectively. The resulting dual-band narrow-linewidth diode lasers have potential for use in a variety of novel applications such as integrated difference-frequency generation, quantum photonics, and nonlinear optics.