双色激光与气体作用产生太赫兹辐射的研究  

Study on Terahertz Emission from Two-Color Lasers Irradiated Gas Targets

作　　者：杨柳[1] 陈燕萍[1] 陈民[1] 徐剑秋[1] 盛政明[1] 

机构地区：[1]上海交通大学物理与天文系激光等离子体教育部重点实验室,上海200240

出　　处：《激光与光电子学进展》2015年第7期267-273,共7页Laser & Optoelectronics Progress

基　　金：国家973计划(2014CB339801)

摘　　要：强激光脉冲与气体靶作用是产生高功率太赫兹(THz)辐射的一个重要途径。利用光电离电流模型研究了同向传播的波长为0.8 mm的激光及其半频光为1.6 mm的激光与气体作用产生强太赫兹辐射的过程。讨论了气体种类、激光振幅、双色激光相位差对离化电流的影响。与通常的0.8 mm激光及其倍频光组合相比,在同等激光强度下利用半频光组合可以产生更强的太赫兹辐射,约为倍频情况下的两倍。通过改变双色激光偏振方向的夹角,当两个光的偏振垂直时,即使半频光的强度远低于基频光,离化电流的方向也由半频光的偏振方向决定。The interaction of ultra-short high power lasers with gas targets is an important way to produce high power terahertz （THz） sources. Based on the model of ionization currents, the THz radiation generation is considered by use of two color lasers at 0.8 μm wavelength and its half-harmonic 1.6 μm co-propagating in a gas target. The influences of the types of gases, the laser amplitudes and the relative phase difference between the two laser pulses on the ionization currents are discussed. Compared with the case with 0.8 μm laser and its second harmonic, the THz radiation amplitude is enhanced twice under the same incident laser amplitude. The effect of the angle between the two laser polarizations is also studied. When the two polarizations are perpendicular to each other, the ionization current direction is along the polarization direction of the half-harmonic laser, even though its amplitude is much lower than that of the fundamental laser.

关 键 词：光谱学 太赫兹辐射 双色激光 离化电流模型 偏振夹角 

分 类 号：O441.4[理学—电磁学]