温稠密金的太赫兹时域光谱实验  

Terahertz Time⁃Domain Spectroscopy of Warm Dense Gold

作　　者：孙旭 吴海忠 王小伟[1] 吕治辉[1] 张栋文[1] 刘东晓[2] 范伟[2] 粟敬钦[2] 周维民[2] 谷渝秋[2] 赵增秀[1] 袁建民[1,3] Sun Xu;Wu Haizhong;Wang Xiaowei;LüZhihui;Zhang Dongwen;Liu Dongxiao;Fan Wei;Su Jingqin;Zhou Weimin;Gu Yuqiu;Zhao Zengxiu;Yuan Jianmin(College of Science,National University of Defense Technology,Changsha 410073,Hunan,China;Science and Technology on Plasma Physics Laboratory,Laser Fusion Research Center,CAEP,Mianyang 621900,Sichuan,China;Graduate School of China Academy of Engineering Physics,Beijing 100193,China)

机构地区：[1]国防科技大学理学院,湖南长沙410073 [2]中国工程物理研究院激光聚变研究中心,等离子体物理全国重点实验室,四川绵阳621900 [3]中国工程物理研究院研究生院,北京100193

出　　处：《中国激光》2023年第17期169-176,共8页Chinese Journal of Lasers

基　　金：国家重点研发计划(2019YFA0307703);国家自然科学基金重点项目(12234020);国家自然科学基金(12374263,12175211,11974425,11974426)

摘　　要：太赫兹波为高能量密度物质提供了独一无二的诊断手段,但在大型高能量密度装置上实现极端条件下物质状态的太赫兹时域光谱诊断技术仍面临巨大挑战。本文报道了在低重复频率、高能量激光装置上开展的光脉冲泵浦-太赫兹探测实验。利用钛宝石飞秒激光器输出焦耳量级的单发脉冲,单发脉冲经磷酸二氢钾倍频后加热30 nm厚自支撑金膜,产生均匀的温稠密金等离子体;同时,将大孔径铌酸锂晶片通过光整流产生的单脉冲能量为7μJ的太赫兹脉冲作为探测光,利用金属阶梯镜实现了单发太赫兹波形探测,获得了温稠密金在太赫兹波段的时间分辨的电导率数据,为检验双温模型中电子-离子耦合系数等关键参数的准确性提供了新基准。Objective Terahertz(THz)waves offer a distinctive diagnostic method for detecting high energy density matter.However,realizing the THz time-domain spectral(THz-TDS)diagnosis of matter states under extreme conditions in large high-energy density devices remains a significant obstacle.To address this requirement,we designed and implemented an optical pump-THz single-shot detection system driven by a strong femtosecond laser.The system possesses the capability of THz single-shot detection under extreme conditions and diagnosis of irreversible processes with extreme transience using THz-TDS diagnosis under intense laser pumping.Methods We developed an integrated optically pumped terahertz(THz)single-shot detection system that utilizes a 45 TW Ti∶sapphire femtosecond laser with a pulse width of 30 fs,central wavelength of 800 nm,and spot diameter of approximately 38 mm.The laser pulses were initially directed to realize second harmonic generation(SHG)via KDP crystals and then separated into fundamental and SHG using a dichroic mirror(DM).The SHG was reflected into the pump time-delay line(TD2)and focused by a lens to ensure complete pumping of the target object with a focus size of approximately 2 mm in diameter consistent with the THz focus size.Meanwhile,the fundamental frequency laser transmitted by the DM was divided by the beam splitting mirror(BS)with 90%of the energy used as the driving laser of the lithium niobate wafer.An intense THz pulse was generated by collinear optical rectification effect,and an off-axis parabolic mirror(OAP)was utilized to focus it onto the target object.The THz pulses transmitted through the target object were focused by the OAP and reflected by indium tin oxide(ITO)to reach the surface of the ZnTe crystal.Moreover,10%of the transmitted energy of the THz probe laser was directed into the time-delay line(TD1)incident with the surface normal of the reflective echelon at 14°and encoded time information into a one-dimensional space.The outgoing laser was spatiotemporal coincident with

关 键 词：超快光学 太赫兹时域光谱 单发泵浦-探测 极端物态诊断 电导率 

分 类 号：O441.4[理学—电磁学]