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attosecond twisted beams from high-order harmonicgeneration driven by optical vortices

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High Power Laser Science and Engineering 2017年第1期5卷 12-19页

作者： Carlos Hernandez-Garcia Laura Rego Julio San Roman Antonio Picon Luis Plaja Grupo de Investigacion en Aplicaciones del Laser y Fotonica Departamento de Fisica AplicadaUniversity of SalamancaE-37008SalamancaSpain Argonne National Laboratory Argonne1L 60439USA

Optical vortices are structures of the electromagnetic field with a spiral phase ramp about a point-phase singularity,carrying orbital angular momentum(OAM). Recently, OAM has been imprinted to short-wavelength radiation through high-order harmonic generation(HHG), leading to the emission of attosecond twisted beams in the extreme-ultraviolet(XUV) regime. We explore the details of the mapping of the driving vortex to its harmonic spectrum. In particular, we show that the geometry of the harmonic vortices is convoluted, arising from the superposition of the contribution from the short and long quantum paths responsible of HHG. Finally, we show how to take advantage of transverse phase-matching to select twisted attosecond beams with different spatiotemporal properties.

关键词： attosecond science extreme-ultraviolet vortices high harmonic generation orbital angular momentum twisted beams vortexbeams

attosecond laser station

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Chinese Physics B 2018年第7期27卷 50-65页

作者： Hao Teng Xin-Kui He Kun Zhao Zhi-Yi Wei Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Science University of Chinese Academy of SciencesBeijing 100049China

The attosecond laser station （ALS） at the Synergetic Extreme Condition User Facility （SECUF） is a sophisticated and user-friendly platform for the investigation of the electron dynamics in atoms, molecules, and condensed matter on timescales ranging from tens of femtoseconds to tens of attoseconds. Short and tunable coherent extreme-ultraviolet （XUV） light sources based on high-order harmonic generation in atomic gases are being developed to drive a variety of endstations for inspecting and controlling ultrafast electron dynamics in real time. The combination of such light sources and end-stations offers a route to investigate fundamental physical processes in atoms, molecules, and condensed matter. The ALS consists of four beamlines, each containing a light source designed specifically for application experiments that will be performed in its own end-station. The first beamline will produce broadband XUV light for attosecond photoelectron spectroscopy and attosecond transient absorption spectroscopy. It is also capable of performing attosecond streaking to characterize isolated attosecond pulses and will allow studies on the electron dynamics in atoms, moleculars, and condensed matter. The second XUV beamline will produce narrowband femtoseeond XUV pulses for time-resolved and angle-resolved photoelectron spectroscopy, to study the electronic dynamics on the timescale of fundamental correlations and interactions in solids, especially in superconductors and topological insulators. The third beamline will produce broadband XUV pulses for attosecond coincidence spectroscopy in a cold-target recoil-ion momentum spectrometer, to study the ultrafast dynamics and reactions in atomic and molecular systems. The last beamline produces broadband attosecond XUV pulses designed for time-resolved photoemission electron microscopy, to study the ultrafast dynamics of plasmons in nanostructures and the surfaces of solid materials with high temporal and spatial resolutions simultane

关键词： attosecond extreme-ultraviolet (XUV) pulse pump-probe photoemission spectroscopy

All-optical attosecond time domain interferometry

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National Science Review 2021年第10期8卷 15-22页

作者： Zhen Yang Wei Cao Yunlong Mo Huiyao Xu Kang Mi Pengfei Lan Qingbin Zhang Peixiang Lu Wuhan National Laboratory for Optoelectronics and School of Physics Huazhong University of Science and Technology Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan Institute of Technology CAS Center for Excellence in Ultra-intense Laser Science

Interferometry, a key technique in modern precision measurements, has been used for length measurement in engineering metrology and astronomy. An analogous time-domain interferometric technique would represent a significant complement to spatial domain applications and require the manipulation of interference on extreme time and energy scales. Here, we report an all-optical interferometer using laser-driven high order harmonics as attosecond temporal slits. By controlling the phase of the temporal slits with an external field, a time domain interferometer that preserves both attosecond temporal resolution and hundreds of me V energy resolution is implemented. We apply this exceptional temporal resolution to reconstruct the waveform of an arbitrarily polarized optical pulse, and utilize the provided energy resolution to interrogate the abnormal character of the transition dipole near the Cooper minimum in argon. This novel attosecond interferometry paves the way for high precision measurements in the time-energy domain using all-optical approaches.

关键词： interferometry attosecond all-optical precision measurement

Helicity of harmonic generation and attosecond polarization with bichromatic circularly polarized laser fields

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Chinese Physics B 2019年第10期28卷 321-326页

作者： Jun Zhang Tong Qi Xue-Fei Pan Jing Guo Kai-Guang Zhu Xue-Shen Liu College of Instrumentation and Electrical Engineering Jilin UniversityChangchun 130026China Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China

We theoretically investigate the high-order harmonic generation(HHG) of helium atom driven by bichromatic counterrotating circularly polarized laser fields. By changing the intensity ratio of the two driving laser fields, the spectral chirality of the HHG can be controlled. As the intensity ratio increases, the spectral chirality will change from positive-to negativevalue around a large intensity ratio of the two driving fields when the total laser intensity keeps unchanged. However, the sign of the spectral chirality can be changed from positive to negative around a small intensity ratio of the two driving fields when the total laser intensity changes. At this time, we can effectively control the helicity of the harmonic spectrum and the polarization of the resulting attosecond pulses by adjusting the intensity ratio of the two driving laser fields. As the intensity ratio and the total intensity of the driving laser fields increase, the relative intensity of either the left-circularly or right-circularly polarized harmonic can be enhanced. The attosecond pulses can evolve from being elliptical to near linear correspondingly.

关键词： high-order harmonic generation bichromatic circularly polarized laser fields spectral chirality attosecond polarization

Quantum model simulations of attosecond electron diffraction

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Science China(Physics,Mechanics & Astronomy) 2010年第6期53卷 987-1004页

作者： Peter BAUM Jrn MANZ Axel SCHILD Max-Planck-Institute of Quantum Optics and Ludwig-Maximilians-Universitt München Freie Universitt Berlin Institut für Chemie und Biochemie

Ultrafast diffraction with free attosecond electron pulses promises insight into the four-dimensional motion of charge density inatoms,molecules and condensed matter. Here we consider the quantum dynamics of the electron-electron scattering process on anattosecond time scale. By numerically solving the time-dependent two-electron Schrdinger equation,we investigate the interactionof an incoming keV-range electron wavepacket by the bound electron of an aligned H+2 molecule,using a one-dimensional *** findings reveal the ratio of elastic to inelastic contributions,the role of exchange interaction,and the influence of the molecularelectron density to diffraction. Momentum transfer during the scattering process,from the incoming to the bound electron mediatedby the nuclei,leaves the bound electron in a state of coherent oscillation with attosecond recurrences. Entanglement causes relatedstate-selective oscillations in the phase shift of the scattered electron. Two scenarios of distinguishable and indistinguishable freeand bound electrons yield equivalent results,irrespective of the electronic spins. This suggests to employ the scenario of distinguishable electrons,which is computationally less demanding. Our findings support the possibility of using electron diffraction forimaging the motion of charge density,but also suggest the application of free electron pulses for inducing attosecond dynamics.

关键词： ultrafast electron diffraction scattering theory attosecond dynamics entanglement coherence

Carrier Envelope Phase Description for an Isolated attosecond Pulse by Momentum Vortices

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Chinese Physics Letters 2019年第6期36卷 24-28页

作者： Meng Li Gui-zhong Zhang Xin Ding Jian-quan Yao College of Precision Instrument and Optoelectronics Engineering Tianjin University Civil Aviation Meteorological Institute Key Laboratory of Operation Programming & Safety Technology of Air Traffic Management Civil Aviation University of China

As a crucial parameter for a few-cycle laser pulse, the carrier envelope phase(CEP) substantially determines the laser waveform. We propose a method to directly describe the CEP of an isolated attosecond pulse(IAP) by the vortex-shaped momentum pattern, which is generated from the tunneling ionization of a hydrogen atom by a pair of time-delayed, oppositely and circularly polarized IAP-IR pulses. Superior to the angular streaking method that characterizes the CEP in terms of only one streak, our method describes the CEP of an IAP by the features of multiple streaks in the vortex pattern. The proposed method may open the possibility of capturing sub-cycle extreme ultraviolet dynamics.

关键词： Isolated attosecond Pulse Momentum Vortices carrier envelope phase(CEP)

静电场中高斯激光束与电子作用产生单个阿秒脉冲

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光电子．激光 2018年第5期29卷 567-574页

作者：朱金荣佟国栋夏长权扬州大学物理科学与技术学院江苏扬州225002

提出了利用线极化的高斯光束穿过固体表面与其电离的一个电子在Thomson散射作用下产生单个阿秒脉冲辐射的方法。发现了上述环境中有合适大小均匀静电场的情况下可以产生单个阿秒脉冲。分别研究了4种不同强度的静电场大小对处在光场半腰... 详细信息

提出了利用线极化的高斯光束穿过固体表面与其电离的一个电子在Thomson散射作用下产生单个阿秒脉冲辐射的方法。发现了上述环境中有合适大小均匀静电场的情况下可以产生单个阿秒脉冲。分别研究了4种不同强度的静电场大小对处在光场半腰束位置的电子产生脉冲的影响。结果显示在相同参数,束腰半径r_0=5,脉冲宽度w_0=3,持续周期时间为200ms,P=1的情况下,四种不同大小静电场环境中均可以产生阿秒脉冲。但是只有当高斯光速强度为5,静电场大小为归一化的E_s=5×10^(-4)时,可以产生单个阿秒脉冲,脉冲宽度为16as。并且比无其他静电场产生脉冲的强度更强,方向单一化。因此得出高斯强度E_s=5×10^(-4)的静电场与静止的单个电子作用可以得出单个阿秒脉冲辐射。

关键词： attosecond pulse 高斯光束非线性Thomson Scattering 单电子运动

Influence of intraband motion on the interband excitation and high harmonic generation

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Chinese Physics B 2019年第9期28卷 9-15页

作者： Rui-Xin Zuo Xiao-Hong Song Xi-Wang Liu Shi-Dong Yang Wei-Feng Yang Research Center for Advanced Optics and Photoelectronics Department of PhysicsCollege of ScienceShantou UniversityShantou 515063China Department of Mathematics College of ScienceShantou UniversityShantou 515063China Key Laboratory of Intelligent Manufacturing Technology(Shantou University) Ministry of EducationShantou 515063China

Tunnelling, acceleration, and collision of electrons are the basic events in the process of high harmonic generation(HHG) in strong-field interaction with ***, the periodic array of atoms in semiconductor structure makes three steps become interatomic coherent process which leads to complicated carrier dynamics and two sources of high harmonic emission: interband polarization and intraband *** difference of features of high harmonic generation between semiconductors and atoms is strongly linked to the unique presence of intraband motion which manifests itself a nontrivial role in intertwined two ***, we review recent experimental and theoretical advances of understanding coupled interband and intraband mechanisms of HHG in *** we focus on the influence of intraband motion on the interband excitation, and on the subsequent HHG emission and attosecond pulse generation.

关键词： high harmonic generation interband polarization intraband current attosecond pulse generation

Controlling paths of high-order harmonic generation by orthogonal two-color fields

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Chinese Physics B 2020年第4期29卷 242-245页

作者： Ze-Hui Ma Cai-Ping Zhang Jun-Lin Ma Xiang-Yang Miao College of Physics and Information Engineering Shanxi Normal UniversityLinfen 041004China Key Laboratory of Spectral Measurement and Analysis of Shanxi Province Shanxi Normal UniversityLinfen 041004China

Controlling paths of high-order harmonic generation from H^2+ is theoretically investigated by numerically solving the time-dependent Schrodinger equation based on the Born-Oppenheimer approximation in orthogonal two-color *** simulations show that the change of harmonic emission paths is dependent on time-dependent distribution of *** with one-dimensional linearly polarized long wavelength laser,multiple returns are suppressed and short paths are dominant in the process of harmonic emission by two-dimensional orthogonal ω/2ω laser ***,not only are multiple returns weaken,but also the harmonic emission varies from twice to once in an optical cycle by orthogonalω/1.5ωlaser *** the time-frequency distributions and the time-dependent electron wave packets probability density,the mechanism of controlling paths is further *** a result,a 68-as isolated attosecond pulse is obtained by superposing a proper range of the harmonics.

关键词： high-order harmonic generation orthogonal two-color fields attosecond pulse generation