基于精密波长计的外腔半导体激光长期稳频系统

Long-term frequency stabilization system of external cavity semiconductor laser based on precision wavelength meter

为抑制连续激光器的长期频率漂移,以精密波长计为参考频率标准,由计算机控制可实现连续激光无调制稳频。此方法从计算机获取波长计数据,利用数字比例积分微分(PID)计算出输出给激光器的反馈电压值,从而修正激光器腔长、实现激光器频率的锁定。此方法可用于目前商业激光器光谱范围内的任意波长,能在激光器频率可调节范围内任意频率点进行锁定。用此方法实现了对631 nm外腔半导体激光器的锁定,获得了1 h频率不确定度为7.4 MHz、长期频率漂移率为士1.1 MHz/h的稳定锁定。

In order to suppress the long-term frequency drift of CW lasers, continuous laser modulation-free frequency stabilization can be realized by computer control with precision wavelength meter as reference frequency standard. The method obtains the wavelength meter data from computer, and the feedback voltage value output to laser is calculated by using digital proportion-integral-derivative （PID）. Thus the laser cavity length is modified, and the laser frequency is locked. This method can be applied to any given wavelength within spectral range of a commercially available laser, and can lock the laser to any absolute frequency within its tunable frequency range. The locking of 631 nm external cavity semiconductor laser is achieved with this method, and the stable locking with frequency uncertainty of 7.4 MHz for an hour, long-term frequency drift rate of 4-1.1 MHz/h is obtained.