All-fiber 770 nm Laser Based on Second Harmonic Generation

We present an all-fiber 770 nm laser module based on second harmonic generation (SHG) in a periodically poled lithium niobate (PPLN) waveguide. The laser module provides an output power of 192 mW with an SHG conversion efficiency of 22.9 %. The side mode suppression ratio (SMSR) of 38.6 dB, and the relative intensity noise (RIN) below -120 dBc/Hz between 100 Hz and 10 MHz Fourier frequency is achieved. The laser linewidth of 15 kHz is acquired. The high optical power and low noise of the 770 nm all-fiber laser module are suitable for precise quantum measurements, such as atomic magnetometers and optical atomic clocks.