摘要
强场飞秒激光作用于原子时,原子中的电子除了发生多光子电离、隧穿电离等过程外,还有很大的概率处于高激发态。这种高激发态的原子在超强超短激光场中非常稳定,并且与强场中的其它许多现象密切相关,例如,中性粒子加速、多光子拉比振荡、近阈值谐波辐射等,因此近十几年来是强场超快物理领域的研究热点之一。在这些研究中,强激光场中里德堡原子的产生机制、激光对里德堡态的调控、里德堡态强场电离及稳定性等,是关注的主要问题。本文将概述强激光驱动的里德堡态的产生机制,包括多光子共振激发,受挫隧穿电离等。重点介绍强激光场驱动的里德堡态原子激发过程中的多种干涉现象。这些干涉现象提供了里德堡原子强场激发的动态过程信息。同时,还将介绍激发态原子在强激光场中的电离过程,特别是圆偏光驱动的里德堡原子电离的圆二色性。
When atoms are exposed to strong femtosecond laser fields,there is a high probability that the electrons in atoms can be excited to the Rydberg states with very high principal quantum numbers and large orbitals,in addition to processes such as multiphoton ionization and tunneling ionization.This highly excited state of the atom is very stable in the ultrashort strong laser pulse and is closely related to many other phenomena in the strong field,such as neutral particle acceleration,multiphoton Rabi oscillations,near-threshold harmonic radiation.It has become one of the research hotspots in the field of strong-field ultrafast physics in the last decade.Among these studies,the mechanism of the generation of Rydberg atoms in strong laser fields,the modulation of Rydberg states by lasers,and the strong-field ionization process and stability of Rydberg states are the main issues of interest.This review provided an overview of the generation mechanisms of the Rydberg states driven by strong laser fields.There are two mechanisms for strong field Rydberg state excitation.One is multiphoton resonance excitation and the other is Frustrated Tunneling Ionization(FTI)excitation.The dependence of the yield of the Rydberg state atoms on the laser ellipticity is usually considered to be an important basis for determining whether the Rydberg state atom generation mechanism is multiphoton resonance excitation or frustrated tunneling ionization.However,this judgment is not reliable.As shown in this review,for multiphoton resonance excitation,the yield of Rydberg state atoms also decreases rapidly with increasing laser ellipticity.In contrast,in the nonadiabatic tunneling ionization region,the yield of Rydberg state atoms in FTI does not always decrease with increasing laser ellipticity,instead,it shows an abnormal increase in the yield.There is no clear boundary between these two mechanisms.This review focused on a variety of interference phenomena during the Rydberg-state excitation of atoms driven by strong laser fields,which are
作者
赵勇
周月明
ZHAO Yong;ZHOU Yueming(School of Physics,Huazhong University of Science and Technology,Wuhan 430074,China)
出处
《光子学报》
EI
CAS
CSCD
北大核心
2023年第7期99-122,共24页
Acta Photonica Sinica
基金
国家重点基础研究发展计划(No.2019YFA0308300)。
关键词
里德堡态原子
强场激发
强场电离
电子波包干涉
圆二色性
Rydberg state atom
Strong field excitation
Strong field ionization
Wavepacket interference
Circular dichroism
