基于声光移频的激光侦测正交解调方法

Quadrature Demodulation in a Laser-interception System Based on Acousto-optic Frequency Shifting

针对激光侦测信号调制与传输特点,提出一种基于多普勒移频的激光侦测系统,研究声光多普勒移频效应理论,探讨相干光平衡探测与正交解调原理,从数值仿真和频域分析了系统抗噪性能及载频失配对信号恢复的影响,给出基于声光移频效应的相干平衡激光侦测的技术实现方法.实验结果表明,基于相干平衡探测与正交解调的激光侦测系统可有效抑制基底及过剩强度噪声对系统输出的影响,进一步提高接收信噪比,实现声波振动对界面产生微扰的非接触信号检测,为实际应用提供一种有效的技术途径.

According to modulation and transmission characteristics of laser interception,a laserinterception system based on Doppler frequency shift was put forward.The theory of Doppler frequency shift was studied,and the optical coherent balanced detection and quadrature demodulation were discussed.The effects of anti-noise performance and carrier-frequency mismatching on signal recovery were analyzed by numerical simulation and frequency-domain analysis,a technical method for laser coherent balanced interception based on acousto-optic frequency shift was proposed.Experimental results show that noise floor and excess intensity noise can be effectively suppressed by the proposed method,namely signal noise ratio can be improved,and thus non-contact detection for the perturbation at interface generated by acoustic vibration can be realized,which provides an effective technical method for practical application.