摘要
利用中红外飞秒激光激发CO_(2)^(+)产生的前向相干辐射现象进行了系统研究。实验发现在泵浦激光与CO_(2)^(+)的A^(2)П_(u)(V′=1)-X^(2)П_(g)(v=0)态跃迁发生五光子共振情况下,CO_(2)^(+)发出的波长为337 nm的前向相干辐射能够被有效激发。更进一步,利用泵浦–探测方法对该辐射进行了时间分辨研究。利用探测激光导致的辐射损耗效应,发现在不同的气压条件下,337 nm相干辐射的持续时间均在0.8 ps左右,与气压没有明显关系。基于这一观测结果,提出该辐射的本质是多光子共振导致的自由感应衰变辐射。研究揭示了利用中红外飞秒激光激发二氧化碳离子产生相干辐射的本质,指出了强场激光与原子、分子体系共振相互作用过程中自由感应衰变效应的普遍性。
The forward coherent radiation generated by ionic carbon dioxide molecules excited by tunable mid-infrared femtosecond laser pulses was systematically investigated.The coherent radiation corresponding to the A^(2)П_(u)(V′=1)-X^(2)П_(g)(v=0) transition of the CO_(2)^(+) can be effectively created when the mid-infrared laser was in multiple photon resonance with the transition.Furthermore,a pump-probe method was used to investigate the temporal evolution of the radiation process.Based on the suppression of the 337 nm radiation effect induced by probe laser pulses,it was found that the duration of 337 nm coherent radiation was about 0.8 ps,which showed no obvious dependence on the gas pressure.In view of this observation,the nature of this coherent 337 nm radiation was free induction decay radiation induced by multi-photon resonance.This study not only reveals the nature of coheren emission of carbon dioxide,but also points out the universality of free induction decay effect in the resonant interaction of high-field laser with atoms and molecules.
作者
罗雨
卢琦
张翔
庄骋轩
刘一
LUO Yu;LU Qi;ZHANG Xiang;ZHUANG Chengxuan;LIU Yi(School of Optical-Electrical and Computer Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China)
出处
《上海理工大学学报》
CAS
CSCD
北大核心
2022年第6期546-552,共7页
Journal of University of Shanghai For Science and Technology
基金
国家自然科学基金资助项目(12034013)
国家外专局资助项目(G2021013007)。
关键词
中红外飞秒激光
二氧化碳离子
多光子共振
自由感应衰变
mid-infrared femtosecond laser
carbon dioxide ions
multi-photon resonance
free induction decay
