本文利用Rydberg阶梯型三能级系统的电磁诱导透明光谱实现了509 nm倍频激光器的无调制频率锁定。我们在实验中使用852 nm激光和509 nm激光在铯原子蒸汽池中构成阶梯型三能级体系,852 nm激光器的频率锁定在铯原子6S1／2→6P3／2共振跃迁线上,509 nm激光在铯原子激发态6P3／2→62D5／2 Rydberg态的跃迁频率附近扫描获得了Rydberg态的电磁诱导透明光谱。利用852 nm半导体激光器的频率调制作为参考信号,对探测的电磁诱导透明光谱信号进行解调得到误差信号,实现了509 nm激光器的频率锁定。通过分析误差信号的频谱,对伺服电路的低频和高频反馈参数进行优化,获得的最佳锁定线宽约为533 kHz,最小阿伦方差达到15×10-11。

We present the laser frequency stabilization of the 509 nm frequency double laser using electromagnetically induced transparency spectra,which is appeared from a cascade three-level system based the Rydberg atom.The 852 nm laser and 509 nm laser compose the cascade three-level scheme.The frequency of 852 nm laser is locked on the 6S1／2(F=4)→6P3／2(F′=5) transition line of the cesium atom.While 509 nm laser is scanned near the transition frequency of the atom excited state 6P3／2→62D5／2 Rydberg state,in order to obtain the electromagnetically induced transparency spectra of Rydberg state.The frequency modulation of 852 nm semiconductor laser is used as a reference signal.The error signal,demodulated electromagnetically induced transparency spectra signal,is fed back to realize the frequency locking of 509nm laser.High and low frequency feedback parameters of the servo system are optimized by analyzing the frequency spectrum of error signal with frequency locked.The finally locking linewidth of 509nm laser is about 533 kHz and the minimum Allan variance of 400 s measure time is 15×10-11.