Realization of a hybrid integrated diode laser for visible light

Hybrid integration of a semiconductor amplifier with a feedback circuit containing ring resonators has been widely demonstrated in the infrared. Such lasers provide ultra-narrowband and single-mode oscillation, which can be tuned over a large spectral range, and easily integrated in a photonic circuit. Contrary to this, applications in the visible spectral range, such as precision metrology with optical clocks, rely on bulk optics lasers, which are susceptible to acoustic noise as they cannot be integrated on a chip. To realize hybrid integrated lasers in the visible range, where scattering losses are typically higher than in the infrared, it is required to design a feedback circuit based on low-loss waveguides. Here, we present the first design and realization of a hybrid integrated diode laser in the visible, by integrating an AlGaInP based amplifier with a Si3N4 based feedback circuit. Our experimental results show that the laser can be tuned over a 11 nm wide interval around the central wavelength of 685 nm and that it delivers a single wavelength output power of up to 4.8 mW. This result is of great importance for the development of on-chip narrowband and tuneable light sources in the visible range.