780 nm narrow-linewidth self-injection-locked WGM lasers

Narrow-linewidth lasers operating in the near-infrared provide precise timing synchronization for atomic optical clocks and quantum computers. Crystalline ultra-high-Q optical resonators enable high-performance laser design in a small form factor that allow miniaturization of the devices using the lasers. Here we demonstrate a 780 nm self-injection-locked laser with Hertz-level instantaneous linewidth under single-mode continuous-wave operation. The self-injection locking induced by the whispering gallery mode resonator suppresses the frequency noise and reduces the drift of the free running device.