Frequency stabilization of a semiconductor laser based on gas absorption cell

Active frequency stabilization method is proposed and demonstrated in this paper. The variation of frequency is used as the feedback signal, and the system is composed of a closed current loop of the semiconductor laser. A DSP is used to realize the automatic frequency finding and frequency stabilization. Stable single mode output with a linewidth of less than 100 kHz was obtained. The frequency shift is within 15 MHz in 2 hours.