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频率稳定的激光器在精密计量、高分辨率光谱等许多领域具有重要的应用。使用KTP晶体将Nd:YAG激光器输出的激光(1064nm)倍频到532nm,采用波长调制吸收光谱技术获得吸收峰的一次谐波信号作为鉴频信号,并基于数字比例-积分-微分(PID)反馈控制技术,把倍频后的频率稳定在碘分子B-X态(32-0)带的R(56)吸收峰上,在1h的连续测量时间内,频率漂移幅度小于2MHz,远小于多普勒受限的光谱线宽,频率稳定度达到了10-9量级,整套系统可以实现长时间连续工作。使用的数字PID稳频方案,可以有效抑制激光的长期频率漂移,具有方案简单、易于实现的优点,同时显著降低了较大幅度随机噪声对系统稳定性的影响。
Frequency stabilized lasers have important applications in many areas, such as precision metrology and high resolution spectroscopy. The KTP crystal was used to double the frequency of laser output from Nd: YAG laser (1064nm) to 532nm. The first harmonic of the absorption peak was obtained as the frequency-discriminating signal by wavelength-modulated absorption spectroscopy, and the signal was demodulated based on digital proportional-integral-derivative Control technique to stabilize the frequency after multiplication over the R (56) absorption band in the BX state (32-0) of the iodine molecule. The frequency drift is less than 2 MHz during 1 h of continuous measurement, much less than the Doppler frequency Limit the spectral line width, frequency stability reached 10-9 magnitude, the entire system can achieve long hours of continuous work. The digital PID frequency stabilization scheme used can effectively suppress the long-term frequency drift of the laser, has the advantages of simple solution and easy implementation, and significantly reduces the influence of relatively large random noise on system stability.