共振增强单色高次谐波产生  

Generation of Resonantly Enhanced Monochromatic High-Order Harmonics

作　　者：汪丽 薛金星 曾志男[1] 李儒新[1] 徐志展[1] Wang Li;Xue Jinxing;Zeng Zhinan;Li Ruxin;Xu Zhizhan(State Key Laboratory of High Field Laser Physics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海光学精密机械研究所强场激光物理国家重点实验室,上海201800 [2]中国科学院大学材料与光电研究中心,北京100049 [3]中国科学院大学,北京100049

出　　处：《中国激光》2019年第10期39-45,共7页Chinese Journal of Lasers

基　　金：国家自然科学基金(61690223,61521093,11127901,11574332,11774363);中国科学院战略性先导科技专项(B类)(XDB16)

摘　　要：飞秒强激光与气体相互作用产生高次谐波是重要的超快相干光源,模拟发现,中红外飞秒激光脉冲可以通过交流斯塔克效应在原子基态与激发态之间实现多光子共振增强,产生高亮度的单色高次谐波辐射。通过数值求解含时薛定谔方程发现,存在阈值以下共振增强的非常规高次谐波,且在较低光强下存在一个最优光强使其可以达到最高产生效率。时间-频率分析结果表明,该共振增强可通过强场下的二阶交流斯塔克效应实现,其对驱动激光波长不敏感。这种新机制使得中红外波段的飞秒激光脉冲更有利于产生高亮度的超快单色紫外/极紫外(UV/XUV)光源,在凝聚态物理、材料科学等领域具有重要的应用前景。The interaction of an intense femtosecond laser with gas to produce high-order harmonics is an important ultrafast coherent light source.Our simulation shows that a mid-infrared femtosecond laser pulse can enhance the multi-photon resonance between the ground states and excited states of the atom by the ac Stark effect and generate high-brightness monochromatic high-order harmonic radiation.By solving the time-dependent Schr dinger equation,we obtain unusual resonantly enhanced high-order harmonics below the threshold,the intensity of which is strongest at an optimal laser intensity.Further,the time-frequency analysis shows that the resonance enhancement is related to the second-order ac Stark effect in a high field,while insensitive to the laser wavelength.This new mechanism makes mid-infrared femtosecond laser pulses more conducive to the generation of ultra-fast monochrome ultraviolet/extreme ultraviolet light sources with high brightness and has important application prospects in condensed matter physics and materials science.

关 键 词：激光光学 斯塔克效应 单色极紫外光源 飞秒激光 高次谐波 

分 类 号：O434.1[机械工程—光学工程]