注入光有限相干性对衰荡腔测试方法的影响及求解衰荡时间的强度积分法  

Influence of finite coherence of injected light on ring-down cavity measurement method and intensity integral method for ring-down time determination

作　　者：黄知秋 张猛[1,2] 彭志敏 王振[3] 杨乾锁[1,2] Huang Zhi-Qiu;Zhang Meng;Peng Zhi-Min;Wang Zhen;Yang Qian-Suo(Key Laboratory for Mechanics in Fluid Solid Coupling Systems,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China;School of Engineering Science,University of Chinese Academy of Science,Beijing 100049,China;State Key Lab of Power Systems,Department of Energy and Power Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]中国科学院力学研究所,流固耦合系统力学重点实验室,北京100190 [2]中国科学院大学工程科学学院,北京100049 [3]清华大学能源与动力工程系,电力系统与发电设备控制与仿真国家重点实验室,北京100084

出　　处：《物理学报》2023年第18期274-282,共9页Acta Physica Sinica

摘　　要：利用数值模拟和搭建的腔衰荡光谱装置,研究了注入激光有限相干性对注入光与腔纵模耦合过程的影响.注入光的有限相干性导致了频扫过程中耦合脉冲的随机性.随机性主要体现在两个方面:一是随着相干长度的减小,耦合脉冲的随机幅值范围增大.二是随着注入光的相干性变差,耦合脉冲由强度随机演化的单脉冲变为连续多脉冲,整体宽度随着扫频速率的降低而逐渐增大.随着相干性的变差,当使用腔体的光强来关闭注入光时,扫频速度的降低会在一个频率耦合过程中引起不止一次的注入关断和腔衰荡事件,特别是对于当利用腔体的长度进行频扫时.此外,本文提出了一种利用不同时间间隔的强度积分来估计衰荡时间的理论方法,并进行相关的实验验证.实验结果表明,与传统拟合法得到的衰荡时间相比,强度积分法对应的相对误差较小.Using numerical simulation and a constructed cavity ring-down spectroscopy device,the influence of the finite coherence of the injected laser on the coupling process between the injected light and the cavity longitudinal mode is studied.The finite coherence of the injected light leads to the randomness of the coupling pulse during frequency scanning.The randomness is mainly reflected in two aspects.One is that as the coherence length decreases,the random amplitude range of the coupling pulse increases,and the other is that as the coherence of the injected light deteriorates,the coupling pulse changes from a single pulse with intensity evolution into continuous multiple pulses,and the overall width gradually increases with the decrease of the scanning rate.Moreover,with the deterioration of the coherence,when the light intensity of the cavity is used to turn off the injected light,the decrease in the scanning rate can cause more than one injection shut-off and ring-down event in a frequency coupling process,especially when scanning with the length of the cavity.In addition,a theoretical method is proposed to estimate the ring-down time by using the strength integral of different time intervals,and the relevant experimental verification is carried out.The experimental results show that the relative error of the ring-down time obtained by the intensity integration method is smaller than that obtained by the traditional fitting method.

关 键 词：腔衰荡光谱 光相干 衰荡时间 强度积分 

分 类 号：O433[机械工程—光学工程]