We report experimental and theoretical investigations of wavelength dependence of Rydberg state excitation(RSE)process of Ar subject to intense laser fields.By simultaneously measuring ionization and RSE yields of Ar ...We report experimental and theoretical investigations of wavelength dependence of Rydberg state excitation(RSE)process of Ar subject to intense laser fields.By simultaneously measuring ionization and RSE yields of Ar atoms subject to strong laser fields at a series of wavelengths,we obtain the wavelength scaling law of the ratio of Ar^(*)over Ar^(+)with respect to the laser intensity,and this result can be well reproduced by a nonadiabatic model,but not by the classical-trajectory Monte Carlo model.Our results indicate that the nonadiabatic corrections of the photoelectron tunneling exit and tunneling probability play a significant role at shorter wavelengths.Analysis shows that the wavelength dependence phenomenon is due to the interplay of the nonadiabatic effect,wave-packet diffusion and Coulomb focusing effect of the liberated electron.展开更多
Femtosecond enhancement cavity(fsEC) has been proved to be a powerful tool in a diverse range of applications.Here, we report the recent progresses in building an fsEC on kilowatt level average power, with the aim of ...Femtosecond enhancement cavity(fsEC) has been proved to be a powerful tool in a diverse range of applications.Here, we report the recent progresses in building an fsEC on kilowatt level average power, with the aim of realization of intracavity high harmonic generation(HHG) and extension of the wavelength of femtosecond optical frequency comb from infrared(IR) to extreme ultraviolet(XUV). Upon mode-matching optimization and cavity length locking, an intracavity average power of 6.08 kW is reached and the corresponding buildup is 225. After introducing noble gas of Xe into the focus region, clear sign of plasma has been observed. The generated HHG is also coupled out by a sapphire plate placed at Brewster's angle for the fundamental laser. Our work paves the way for the realization of an XUV comb.展开更多
We experimentally investigate the double ionization pulses. The total kinetic energy release of the two of molecular hydrogen subjected to ultrashort intense laser coincident H＋ ions, which provides a diagnosis of di...We experimentally investigate the double ionization pulses. The total kinetic energy release of the two of molecular hydrogen subjected to ultrashort intense laser coincident H＋ ions, which provides a diagnosis of different processes to double ionization of H2, is measured for two different pulse durations, i.e., 25 and 5 fs, and various laser intensities. It is found that, for the long pulse duration （i.e., 25 fs）, the double ionization occurs mainly via two processes, i.e., the charge resonance enhanced ionization and recollision-induced double ionization. Moreover, the contributions from these two processes can be significantly modulated by changing the laser intensity. In contrast, for a few-cycle pulse of 5 fs, only the recollsion-induced double ionization survives, and in particular, this process could be solely induced by the first-return reeollision at appropriate laser intensities, providing an efficient way to probe the sub-laser-cycle molecular dynamics.展开更多
The problem of how long it takes for an electron to tunnel from one side of a barrier to the other has been debated for decades and the attoclock is a promising experimental procedure to address this problem.In the at...The problem of how long it takes for an electron to tunnel from one side of a barrier to the other has been debated for decades and the attoclock is a promising experimental procedure to address this problem.In the attoclock experiment,,many physical effects will contribute to the experimental results and it is difficult to extract the t unneling time accurately.We numerically investigate a method of measuring the residual equivalent temporal offset(RETO)induced by the physical effects except for tunneling delay.The Coulomb potential effect,the nonadiabatic effect,the multielectron effect,and the Stark effect are considered in the theoretical model.It is shown that the ratio of the RETO of the target atoms to that of H is insensitive to the wavelength and is linearly proportional to(2IP)^-3/2.This work can help to improve the accuracy of the attoclock technique.展开更多
Coulomb potential may induce a significant angular offset to the two-dimensional photoelectron momentum distributions for atoms subject to strong elliptically polarized laser fields.In the attoclock experiment,this of...Coulomb potential may induce a significant angular offset to the two-dimensional photoelectron momentum distributions for atoms subject to strong elliptically polarized laser fields.In the attoclock experiment,this offset usually cannot be easily disentangled from the contribution of tunneling delay and poses a main obstacle to the precise measurement of tunneling delay.Based on semiclassical calculations,here,we propose a method to extract the equivalent temporal offset induced solely by Coulomb potential(TOCP)in an attoclock experiment.Our calculations indicate that,at constant laser intensity,the TOCP shows distinctive wavelength dependence laws for different model atoms,and the ratio of the target atom’s TOCP to that of H becomes insensitive to wavelength and linearly proportional to(2Ip)?3/2,where Ip is the ionization potential of the target atom.This wavelength and Ip dependence of TOCP can be further applied to extract the Coulomb potential influence.Our work paves the way for an accurate measurement of the tunneling delay in the tunneling ionization of atoms subject to intense elliptically polarized laser fields.展开更多
基金Supported by the National Key Research and Development Program of China(Grant No.2019YFA0307700)the National Natural Science Foundation of China(Grant Nos.12004391,12104465,12274420,and U21A20435)+5 种基金China Postdoctoral Science Foundation(Grant Nos.2019M662752,2020T1306822022M713219)CAS Project for Young Scientists in Basic Research(Grant No.YSBR-055)the Science and Technology Department of Hubei Province(Grant No.2020CFA029)Knowledge Innovation Program of Wuhan-Shuguang Project(Grant No.2022020801020140)K.C.Wong Education Foundation。
文摘We report experimental and theoretical investigations of wavelength dependence of Rydberg state excitation(RSE)process of Ar subject to intense laser fields.By simultaneously measuring ionization and RSE yields of Ar atoms subject to strong laser fields at a series of wavelengths,we obtain the wavelength scaling law of the ratio of Ar^(*)over Ar^(+)with respect to the laser intensity,and this result can be well reproduced by a nonadiabatic model,but not by the classical-trajectory Monte Carlo model.Our results indicate that the nonadiabatic corrections of the photoelectron tunneling exit and tunneling probability play a significant role at shorter wavelengths.Analysis shows that the wavelength dependence phenomenon is due to the interplay of the nonadiabatic effect,wave-packet diffusion and Coulomb focusing effect of the liberated electron.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674356 and 11527807)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21010400)
文摘Femtosecond enhancement cavity(fsEC) has been proved to be a powerful tool in a diverse range of applications.Here, we report the recent progresses in building an fsEC on kilowatt level average power, with the aim of realization of intracavity high harmonic generation(HHG) and extension of the wavelength of femtosecond optical frequency comb from infrared(IR) to extreme ultraviolet(XUV). Upon mode-matching optimization and cavity length locking, an intracavity average power of 6.08 kW is reached and the corresponding buildup is 225. After introducing noble gas of Xe into the focus region, clear sign of plasma has been observed. The generated HHG is also coupled out by a sapphire plate placed at Brewster's angle for the fundamental laser. Our work paves the way for the realization of an XUV comb.
基金Supported by the National Basic Research Program of China under Grant No 2013CB922201the National Natural Science Foundation of China under Grant Nos 11304365,11374329 and 11334009
文摘We experimentally investigate the double ionization pulses. The total kinetic energy release of the two of molecular hydrogen subjected to ultrashort intense laser coincident H＋ ions, which provides a diagnosis of different processes to double ionization of H2, is measured for two different pulse durations, i.e., 25 and 5 fs, and various laser intensities. It is found that, for the long pulse duration （i.e., 25 fs）, the double ionization occurs mainly via two processes, i.e., the charge resonance enhanced ionization and recollision-induced double ionization. Moreover, the contributions from these two processes can be significantly modulated by changing the laser intensity. In contrast, for a few-cycle pulse of 5 fs, only the recollsion-induced double ionization survives, and in particular, this process could be solely induced by the first-return reeollision at appropriate laser intensities, providing an efficient way to probe the sub-laser-cycle molecular dynamics.
基金Supported by the National Key Research and Development Program of China(Nos.2019YFA0307700 and 2016YFA0401100)the National Natural Science Foundation of China(Nos.11527807,11774387,11834015.11847243,11804374,11874392,and 11974383)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB21010400)the Science and Technology Department of Hubei Province(No.2019CFA035).
文摘The problem of how long it takes for an electron to tunnel from one side of a barrier to the other has been debated for decades and the attoclock is a promising experimental procedure to address this problem.In the attoclock experiment,,many physical effects will contribute to the experimental results and it is difficult to extract the t unneling time accurately.We numerically investigate a method of measuring the residual equivalent temporal offset(RETO)induced by the physical effects except for tunneling delay.The Coulomb potential effect,the nonadiabatic effect,the multielectron effect,and the Stark effect are considered in the theoretical model.It is shown that the ratio of the RETO of the target atoms to that of H is insensitive to the wavelength and is linearly proportional to(2IP)^-3/2.This work can help to improve the accuracy of the attoclock technique.
基金supported by the National Key Research and Development Program of China(Nos.2019YFA0307702,2019YFA0307704,and 2016YFA0401100)the National Natural Science Foundation of China(Nos.11974383,11834015,11847243,11804374,11874392,11774387,11527807,and 11425414)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB21010400)。
文摘Coulomb potential may induce a significant angular offset to the two-dimensional photoelectron momentum distributions for atoms subject to strong elliptically polarized laser fields.In the attoclock experiment,this offset usually cannot be easily disentangled from the contribution of tunneling delay and poses a main obstacle to the precise measurement of tunneling delay.Based on semiclassical calculations,here,we propose a method to extract the equivalent temporal offset induced solely by Coulomb potential(TOCP)in an attoclock experiment.Our calculations indicate that,at constant laser intensity,the TOCP shows distinctive wavelength dependence laws for different model atoms,and the ratio of the target atom’s TOCP to that of H becomes insensitive to wavelength and linearly proportional to(2Ip)?3/2,where Ip is the ionization potential of the target atom.This wavelength and Ip dependence of TOCP can be further applied to extract the Coulomb potential influence.Our work paves the way for an accurate measurement of the tunneling delay in the tunneling ionization of atoms subject to intense elliptically polarized laser fields.
