Hybrid-integrated diode laser in the visible spectral range

Generating visible light with wide tunability and high coherence based on photonic integrated circuits is of interest for applications in biophotonics, precision metrology quantum technology. Here we present the first demonstration a hybrid-integrated diode laser spectral range. Using an AlGaInP optical amplifier coupled to low-loss Si3N4 feedback circuit microring resonators, obtain coverage 10.8 nm around 684.4 wavelength up 4.8 mW output power. The measured intrinsic linewidth 2.3$\pm$0.2 kHz.