【作者】 苏娟； 焦明星； 马源源； 邢俊红；

【Author】 Juan Su;Mingxing Jiao;Yuanyuan Ma;Junhong Xing;Department of Precision Instruments, School of Mechanical and Instrumental Engineering,Xi’an University of Technology;People’s Republic of China.Key Laboratory of Photoelectric Logging and Detecting of Oil and Gas,Ministry of Education,Xi’an Shiyou University;

【机构】 西安理工大学机械与精密仪器工程学院精密仪器系； 西安石油大学光电油气测井与检测教育部重点实验室；

【摘要】 分析了传统Pound-Drever-Hall(PDH)激光稳频方法的工作原理,设计了一种基于正交解调原理的PDH激光稳频方案。该方案采用直接数字频率合成器同时产生两路频率均为10MHz的正弦和余弦信号,其中正弦信号分为两路:一路用于驱动电光相位调制器以产生相位边带,另一路与余弦信号一起作为相位解调的参考信号;经相位调制后的激光束耦合进入F-P参考腔,所产生的光外差干涉信号由光电探测器进行探测,其输出信号分别与两路正交参考信号进行混频,经低通滤波后得到误差信号的两个正交分量,二者经A/D转换后进入微处理器进行正交相敏检波运算,即可得到PDH稳频系统的误差信号,该信号经数字PID运算后得到伺服控制信号,再经D/A转换后作为压电陶瓷的驱动信号以反馈调节激光腔长,从而将激光频率锁定到F-P参考腔的谐振频率处。建立了正交解调PDH激光稳频实验系统,对F-P参考腔的腔长进行线性扫描,观察到了鉴频曲线,其鉴频灵敏度为1.82V/MHz,最大频率变化量为5.48MHz。实验结果表明,所设计的正交解调PDH稳频方案是可行的。更多还原

【Abstract】 The principle of operation of the traditional Pound-Drever-Hall(PDH) method for laser frequency stabilization has been analyzed, based on the principle of quadrature demodulation, a scheme of PDH laser frequency stabilization has been designed,in which both sine and cosine signals with the same frequency of 10 MHz have been generated simultaneously by use of a direct digital synthesizer. The sine signal is divided into two parts, one part is used to drive an electro-optic modulator to produce the phase sidebands, another part together with the cosine signal are used as the reference signals for the phase demodulation. The phase-modulated laser beams are coupled into the reference Fabry-Perot cavity, and the optical heterodyne interference signal can be detected by a photo-detector, whose output is mixed respectively with the two orthogonal reference signals to get the two quadrature components of the error signal after low-pass filtered. By the AD conversations, the two quadrature components are transmitted to the microprocessor to perform the algorithm of orthogonal phase sensitive detection so that the error signal of the PDH frequency-stabilized system is obtained. A servo signal can be obtained by performing the digital PID algorithm, and by the DA conversation, it is employed to drive a piezo-electric transducer to adjust the laser cavity-length so as to lock-in the laser frequency at the resonant frequency of the reference Fabry-Perot cavity. A system of the PDH laser frequency stabilization using quadrature demodulation method has been established and investigated experimentally, and by linearly sweeping the cavity-length of the reference Fabry-Perot cavity, a curve of frequency discrimination has been observed, with a sensitivity of 1.82V/MHz and a maximum frequency change of 5.48 MHz. The experimentally obtained results have shown that the scheme of the PDH laser frequency stabilization system using the quadrature demodulation method is indeed feasible.更多还原