基于光学反馈频率锁定的窄线宽稳定中红外激光产生技术研究  

Research on generation of stable mid-infrared lasers with narrow linewidths based on optical feedback locking

作　　者：杨家齐 赵刚 焦康 高健 闫晓娟[1,2] 赵延霆 马维光[1,2] 贾锁堂 Yang Jia-Qi;Zhao Gang;Jiao Kang;Gao Jian;Yan Xiao-Juan;Zhao Yan-Ting;Ma Wei-Guang;Jia Suo-Tang(State Key Laboratory of Quantum Optics and Quantum Optics Devices,Shanxi University,Taiyuan 030006,China;Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan 030006,China)

机构地区：[1]山西大学,量子光学与光量子器件国家重点实验室,太原030006 [2]山西大学,极端光学协同创新中心,太原030006

出　　处：《物理学报》2024年第1期193-200,共8页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2022YFC3700329);国家自然科学基金(批准号:61905134,61905136,62175139);山西省留学人员科技活动项目(批准号:20220001)资助的课题。

摘　　要：中红外精密激光光谱技术在痕量气体检测、基本物理常数测定等领域都有重要应用,然而由于缺乏窄线宽、稳定的中红外光源,很难实现中红外精密光谱测量.本文介绍了一种基于光学反馈频率锁定的窄线宽稳定中红外激光产生技术,分析了光学反馈实现激光到F-P腔锁定的可行性,利用一个高精细度中红外超稳F-P腔作为频率参考,基于光学反馈技术实现了量子级联激光器到该超稳腔的锁定.经过评估得到激光器线宽被压窄到1.1 Hz,压窄激光线宽的同时稳定了激光频率,将激光器的长期漂移控制在20 kHz/12 h.其中,为了获取长时间稳定的光学反馈,基于PDH技术获取了误差信号,用于对反馈相位的实时伺服控制.Mid-infrared precision spectroscopy has important applications in the fields of trace gas detection and the determination of fundamental physical constants.However,due to the limited commercialization of related technologies,there is a lack of narrow linewidth laser sources or linewidth narrowing approaches in the midinfrared region,as well as stable mid-infrared frequency standards.The most commercialized and widely used mid-infrared laser source is the quantum cascade laser(QCL).But its free-running linewidth is more than MHz scale due to the influence of laser drive current noise and temperature fluctuation.This impedes the development of precision spectroscopy in this region.In this work,we introduce a technique for generating a narrow linewidth,stable mid-infrared laser by using optical feedback frequency locking,with a high-finesse midinfrared ultrastable Fabry-Pérot cavity as the frequency reference.The optical cavity consists of two high reflectivity mirrors separated by ultra-low expansion(ULE) material with a low temperature expansion coefficient,and its temperature is precisely controlled.And the cavity is also surrounded in a vaccum cavity made of stainless steel.All these measures ensure the cavity length and its longitudinal mode stability.By using optical feecback,a QCL is locked to the cavity,which stabilizes the laser frequency and narrows the laser linewidth.In order to improve the long-term stability of the optical feedback,an active servo is leveraged to control the feedback phase.The error signal for the servo is obtained by using the method similar to the PoundDerver-Hall locking.In this work,we first theoretically analyze the feasibility of laser to F-P cavity frequency locking by optical feedback.We propose the laser frequency response model with a linear F-P cavity under optical feedback,and analyze the influence of the direct cavity reflection on the laser frequency.Then the experimental demonstration is conducted.Firstly,we measure the reflectivity of the cavity mirror by using cavity

关 键 词：激光频率锁定 中红外激光 线宽压窄 光学反馈 

分 类 号：TN248[电子电信—物理电子学]