基于调制转移光谱的激光自动锁频系统研究  

Research on Laser Automatic Frequency Locking System Based on Modulation Transfer Spectroscopy

作　　者：陈俊杰 高浚超 周俊杰 叶留贤 吴彬[1] 程冰 王河林[1] 王肖隆 林强[1] CHEN Junjie;GAO Junchao;ZHOU Junjie;YE Liuxian;WU Bin;CHENG Bing;WANG Helin;WANG Xiaolong;LIN Qiang(College of Science,Zhejiang University of Technology,Zhejiang Provincial Key Laboratory of Quantum Precision Measurement,Hangzhou 310023,China)

机构地区：[1]浙江工业大学理学院浙江省量子精密测量重点实验室,杭州310023

出　　处：《光子学报》2024年第12期93-104,共12页Acta Photonica Sinica

基　　金：国家重点研发计划(No.2023YFC2907000)。

摘　　要：激光频率的高稳定性与激光锁频系统脱锁后的快速自动回锁,对于量子重力仪进行长时间外场测量具有重要意义。设计了一套基于调制转移光谱的激光绝对频率自动锁定系统,利用自行搭建的调制转移光谱锁频光路,通过扫描激光器的输出频率得到待锁谱线,然后将其输送至自动锁频运行系统进行相似度识别,利用卷积寻峰算法获得待锁频率点的参考电压信号,再通过反馈控制单元将其输入待锁激光器,实现激光频率的快速自动锁定。激光自动锁频系统测试结果表明,锁频前后频率万级稳定度由6.672×10^(-8)@8000 s提升至1.265×10^(-11)@8000 s,当外界因素造成激光器的输出频率脱锁后,激光自动锁频系统可以在1 s内实现激光频率的快速回锁,且回锁前后的一致性较好。所研制的激光自动锁频系统具有锁频精度高、回锁时间短、结构简单、稳定性强等优点,可满足激光器在无人监守环境下长时间频率锁定的需求,适用于冷原子重力仪、冷原子梯度仪、冷原子陀螺仪及冷原子钟等量子精密测量仪器。The quantum gravimeter has high requirements on the stability of laser frequency when it works in ship-borne,air-borne,space-borne and other external fields.However,due to changes in the external environment and its own instability factors,the center frequency of the laser output will change with time to produce MHz or even GHz magnitude drift,which will cause the laser mode hopping and affect the normal operation of the instrument.Therefore,it is necessary to lock the output frequency of the laser to suppress the frequency drift.The traditional laser frequency locking system needs to manually adjust the working parameters and judge the locking situation,which cannot meet the requirements of long-term stable operation of quantum precision measuring instruments without manual intervention.In this paper,a set of laser absolute frequency automatic locking system is designed by using the advantages of modulation transfer spectroscopy,such as flat zero background signal,large slope of error signal,high frequency stability(above 10^(-8) order of magnitude),small frequency line drift and easy locking.Firstly,based on the semiconductor laser,a frequency-locked optical path suitable for modulation transfer spectroscopy is built,and the 16-bit analog-to-digital converter is used to read the modulation transfer spectroscopy signal at high speed and send it to the automatic frequency locking operation system.The core of the laser automatic frequency locking operation system is the automatic frequency locking state machine,which contains six states:initialization state,scanning state,similarity recognition state,locking state,monitoring state and waiting for locking state.After the automatic frequency locking process is turned on,the convolution peak-seeking algorithm is used in the state machine to find the required characteristic spectrum information and obtain the reference voltage signal of the frequency point to be locked,and then the reference voltage signal is sent to the laser to be locked through the feedback control

关 键 词：量子重力仪 自动锁频 卷积寻峰 激光 调制转移光谱 频率稳定度 回锁时间 

分 类 号：TN249[电子电信—物理电子学]