双调制深度大线性动态范围自适应PDH稳频方法  

Adaptive PDH Frequency Stabilization Method with Large Linear Dynamic Range Based on Two Modulation Depths

作　　者：严利平[1] 张哲伟 谢建东[1] 楼盈天[1] 陈本永[1] Yan Liping;Zhang Zhewei;Xie Jiandong;Lou Yingtian;Chen Benyong(Precision Measurement Laboratory,Zhejiang Sci-Tech University,Hangzhou 310018,Zhejiang,China)

机构地区：[1]浙江理工大学精密测量技术实验室,浙江杭州310018

出　　处：《光学学报》2023年第19期115-126,共12页Acta Optica Sinica

基　　金：国家重点研发计划(2022YFF0705803);浙江省科技创新领军人才项目(2022R52052);浙江理工大学科研业务费专项资金资助(23222095-Y)。

摘　　要：针对Pound-Drever-Hall(PDH)技术存在的线性动态范围窄、抗干扰能力弱的问题,提出一种基于双调制深度+双误差信号的PDH稳频方法。首先采用数字正交解调技术精确提取干涉信号相位以实现本振信号相位和干涉信号相位的自动匹配;然后利用透射功率信号Ptran和传统误差信号SPDH构建一个新误差信号Spre,以扩大PDH稳频系统的线性动态范围;接着,采用大调制深度对应的新误差信号Spre实现快速捕获和预锁定;最后,采用小调制深度对应的误差信号SPDH实现精确锁定。锁定后,可根据Ptran幅值变化自动切换调制深度和误差信号,实现大线性动态范围和高灵敏度的PDH稳频。研制了基于现场可编辑逻辑门阵列(FPGA)的稳频控制系统,对法布里-珀罗腔进行了锁定测试。实验结果表明,双调制深度+双误差信号的自适应锁定机制可极大地提高锁定系统的抗干扰能力,且锁定精度高,3小时腔长相对稳定度达5.72×10-9,所提方法可以广泛应用于激光频率/谐振腔锁定等领域。Objective To solve the problems of narrow linear dynamic range and weak anti-interference ability of the Pound-Drever-Hall(PDH)technique,a PDH frequency stabilization method based on two modulation depths and two error signals is proposed herein.The PDH technique is widely used in the fields of laser frequency or optical resonant cavity locking.The traditional PDH technique usually utilizes a modulation depth of 1.08 rad to obtain the most sensitive error signal.However,the traditional PDH technique,used for frequency stabilization,is susceptible to environmental disturbances and loss of lock owing to the narrow linear dynamic range of error signals.In addition,only when the phase of a local demodulation signal matches the phase of an interference signal reflected by the cavity,the error signal with the highest sensitivity can be obtained.Currently,most methods manually adjust the initial phase of the local demodulation signal to achieve phase matching;these methods exhibit low accuracy and cannot realize automatic locking easily.Therefore,an adaptive locking mechanism having large modulation depth with large linear dynamic range error signal and small modulation depth with high-sensitivity error signal is developed to achieve frequency stabilization with strong antiinterference ability and high precision.Methods First,a digital quadrature demodulation technique was used to accurately extract the phase of the interference signal to achieve automatic matching between the phases of the local demodulation and interference signals.Second,a new error signal(Spre)was realized using the transmitted power signal Ptran and traditional error signal SPDH to enlarge the linear dynamic range of the PDH frequency stabilization system.Then,Spre corresponding to the large modulation depth was used to realize fast capture and prelocking.Finally,SPDH corresponding to the small modulation depth was used to realize precise locking.After locking,the modulation depths and error signals could be automatically switched according to the

关 键 词：Pound-Drever-Hall稳频 线性动态范围 法布里-珀罗腔 相位匹配 数字正交解调 

分 类 号：O436[机械工程—光学工程]