宽调谐高脉冲能量的短波红外光学参量振荡器  

Widely Tunable and High Pulse Energy Short⁃Wave Infrared Optical Parametric Oscillator

作　　者：刘鹏翔 李伟 祁峰[2,3] 牛春草[1,2,3] 李惟帆 付俏俏 郭丽媛 李忠洋 Liu Pengxiang;Li Wei;Qi Feng;Niu Chuncao;Li Weifan;Fu Qiaoqiao;GuoLiyuan;Li Zhongyang(College of Information Engineering,Shenyang University of Chemical Technology,Shenyang 110142,Liaoning,China;Shenyang Institute of Automation,Chinese Academy of Sciences,Shenyang 110169,Liaoning,China;Key Laboratory of Liaoning Province in Terahertz Imaging and Sensing,Shenyang 110169,Liaoning,China;University of Chinese Academy of Sciences,Beijing 100049,China;College of Electric Power,North China University of Water Resources and Electric Power,Zhengzhou 450045,Henan,China)

机构地区：[1]沈阳化工大学信息工程学院,辽宁沈阳110142 [2]中国科学院沈阳自动化研究所,辽宁沈阳110169 [3]辽宁省太赫兹成像与感知重点实验室,辽宁沈阳110169 [4]中国科学院大学,北京100049 [5]华北水利水电大学电力学院,河南郑州450045

出　　处：《中国激光》2023年第23期186-191,共6页Chinese Journal of Lasers

基　　金：中国科学院青年创新促进会(2019204);雄安新区科技创新专项任务(2022XAGG0181);辽宁省“兴辽英才”计划(XLYC200774)。

摘　　要：利用Nd∶YAG激光泵浦磷酸氧钛钾晶体,实现了波长为2.05~2.97μm的相干光输出,其覆盖了近红外与中红外过渡波段(也称“短波红外波段”)。采用了与以往报道不同的相位匹配调谐区域,在较小的晶体转角下,获得了较宽的调谐范围。比较了单程与双程泵浦的两种光学参量振荡器结构,验证了双程泵浦的优越性。双程泵浦的光学参量振荡器的最高输出脉冲能量在18 mJ以上,峰值功率高于2.3 MW,在较宽调谐范围内保持了较高的输出能量,输出能量在5 mJ以上的波段占比为78.3%。上述工作为短波红外波段应用提供了一种便捷有效的相干光源。Objective The 2‒3μm short-wave infrared band exhibits unique properties during interactions with gas molecules and biological tissues.Thus,it finds applications in various domains such as remote sensing of greenhouse gases,atmospheric pollution,and medical treatments.Coherent sources in this band play a key role in the above fields and the tunability of the coherent sources is an important factor,especially in multiple molecule spectroscopy.OPOs have proved to be effective light sources with desired wavelengths,owing to the following merits:the commercial availability of well-developed lasers and nonlinear crystals,coupled with their agile frequency tunability.Bulk KTiOPO4(KTP)serves as an excellent OPO medium owing to its high optical damage threshold,moderate nonlinearity,wide phase-matching(PM)wavelength region,and low cost.However,most previous studies focused on doubly resonant operation at wavelengths below 2.4μm.In this study,we perform an experimental analysis of nearly singly resonant KTP-OPO with a wide tuning range of 2.05‒2.97μm under a small rotation angle.Methods A commonly used PM geometry of Nd∶YAG laser pumping KTP-OPO(type-II,θ-tuning in the x-z plane)is presented in Fig.1.In the range ofθ<50°,the output wavelength changes rapidly with the PM angle.Thus,a KTP cut atθ≈48°incorporating properly coated cavity mirrors can theoretically perform a singly resonant OPO,covering 2.2‒3.0μm under a rotation(external)angle of±4°.The experimental setup of the OPO is illustrated in Fig.2.A Q-switched Nd∶YAG laser is used as the pump source.The pump pulses pass through a variable attenuator(comprising a half-wave plate and a Brewster polarizer)and an isolator(ISO)and are incident on a plane-parallel OPO cavity.Two configurations are tested:single-pass OPO(SP-OPO)and double-pass OPO(DPOPO).In the first case,the cavity mirrors M3 and M4 are identical(CaF2 coated with high-reflection films at 1.65‒2.00μm and antireflection films at 1.06μm and 2.2‒3.0μm)with a spacing of 28 mm.Two lon

关 键 词：非线性光学 光学参量振荡器 短波红外波段 磷酸氧钛钾 角度调谐 

分 类 号：O437[机械工程—光学工程]