相位调制光外差稳频信号检测技术

在高功率条件下，由于受到多种因素的影响，单频光纤激光器输出激光的谱线宽度大幅展宽，输出激光的稳定性也不高。相位调制光外差稳频（PDH）技术在高功率条件下可以实现高频率稳定性。为实现对中心波长为1 064 nm的单频光纤激光器的稳频，理论分析了PDH稳频系统的原理并搭建PDH稳频系统。实验发现100 MHz相位调制光外差信号的检测是稳频系统的关键。实验中首先利用自行设计的探测器前置放大电路，基于Si探测器，实现了信号的探测和放大；其次，设计解调电路，通过将光电转换后的信号与参考信号进行混频实现解调，得到鉴频曲线，实现对光外差信号的检测。

PDH frequency stabilization signal detection technology

In high power condition, not only the linewidth of single frequency fiber laser becomes wider greatly, but also its frequency stability becomes worse because of effects of many factors. PDH frequency stabilization technology can be applied in high-power condition with high frequency stability. To realize stable output of high power 1 064 nm single frequency fiber laser, the principle of PDH frequency stabilization technology was analyzed and a PDH optical heterodyne frequency stabilization system was established. It is found that the key of the PDH system is the detection of 100 MHz phase modulation optical heterodyne signal. Firstly, the optical signal was detected and amplified by Si detector with self-designed preamplifier circuit. Secondly, demodulation circuit was designed and the amplified signal and a reference signal were mixed together with a mixer to realize demodulation, as a result, the frequency discrimination curve was obtained. This indicates that the detection of the optical heterodyne signal has been realized.