A hybrid-integrated diode laser for the visible spectral range

Hybrid integrated diode lasers operating in the visible spectrum are of high interest for, e.g., biophotonics and metrology. This type of laser provides single longitudinal mode oscillation with a wide wavelength tunability and a narrow spectral linewidth, by coupling a semiconductor optical amplifier to a micro-ring resonator based photonic circuit. So far, such lasers have only operated at infrared wavelengths. Here we present the first such laser operating in the visible. The laser comprises an AlGaInP gain section coupled to a Si3N4 feedback circuit and exhibits a spectral coverage of 10.8 nm around 684.4 nm with up to 4.8 mW output power. The measured intrinsic linewidth is 2.4±0.1 kHz.