1. College of Metrology & Measurement Engineering, China Jiliang University, Hangzhou, Zhejiang 310018, China
2. National Institute of Metrology, Beijing 100029, China
3. School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China
Abstract：A high stability laser frequency stabilization method based on optical phase-locked loop is reported to improve the frequency stability and accuracy of a tunable external cavity semiconductor laser (TECDL). Self-developed optical phase-locked loop circuit adopts the combination of digital phase discrimination and difference operation to obtain the high sensitivity frequency phase discrimination error signal, and realizes the closed-loop locking of the whole system through high-speed analog PID. Experimental results of TECDL offset locking to optical frequency comb (OFC) show that the frequency fluctuation is within ±0.3Hz after the loop locking. When the offset frequency is 50MHz, the Allan deviation of OPLL system of 1 s and 1000 s integration time is 1.5×10-9 and 8.5×10-13, respectively. The research shows that the sub-Hz laser frequency difference control can be realized by using the laser frequency stabilization method based on optical phase-locked loop. By offset locking the TECDL to the reference laser source with high stability, its frequency stability can be significantly improved, so that it can meet the requirements of laser frequency stability and accuracy in the fields of ultra-precision measurement and cold atom/ion interferometry.
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2022, Vol. 43 
