scispace - formally typeset
Search or ask a question
Author

Shancai Zhang

Bio: Shancai Zhang is an academic researcher from University of Science and Technology of China. The author has contributed to research in topics: Laser & Physics. The author has an hindex of 2, co-authored 7 publications receiving 19 citations.
Topics: Laser, Physics, Terahertz radiation, Optics, Chirp

Papers
More filters
Journal ArticleDOI
TL;DR: FELiChEM is a new experimental facility under construction at the University of Science and Technology of China (USTC), whose core device is two free electron laser oscillators generating middle infrared and far-infrared laser and covering the spectral range of 2.5-200 μm.
Abstract: FELiChEM is a new experimental facility under construction at the University of Science and Technology of China (USTC). Its core device is two free electron laser oscillators generating middle-infrared and far-infrared laser and covering the spectral range of 2.5–200 μm. It will be a dedicated infrared light source aiming at energy chemistry research. We present the brief design of the FEL oscillators, with the emphasis put on the middle-infrared oscillator. Most of the basic parameters are determined and the anticipated performance of the output radiation is given. The first light of FELiChEM is targeted for the end of 2017.

23 citations

Journal ArticleDOI
TL;DR: FELiChEM is a new experimental facility under construction at University of Science and Technology of China (USTC), whose core device is two free electron laser oscillators generating middle infrared and far-infrared laser and covering the spectral range of 2.5-200 $m as discussed by the authors.
Abstract: FELiChEM is a new experimental facility under construction at University of Science and Technology of China (USTC), whose core device is two free electron laser oscillators generating middle-infrared and far-infrared laser and covering the spectral range of 2.5-200 $\mu$m. It will be a dedicated infrared light source aiming at energy chemistry research. We present the brief design of FEL oscillators with the emphasis put on the middle-infrared oscillator. Most of the basic parameters are determined and the anticipated performance of the output radiation is given. The first light of FELiChEM is targeted for the end of 2017.

8 citations

Journal ArticleDOI
TL;DR: A novel photomixing scheme is presented to generate a longitudinally modulated laser pulse with non-uniform time intervals between the adjacent micro-peaks, which means that there is a chirp in the modulation frequency, and this chirP can be continuously tuned.
Abstract: It is of scientific significance to explore the terahertz radiation source with the performances of high power, tunable frequency, and controllable chirp for the realization of coherent control of quantum systems. How to realize frequency chirp control of terahertz synchrotron radiation is the last puzzle to be completed. In this Letter, we propose a method to control the radiation frequency chirp with precision. A novel photomixing scheme is presented to generate a longitudinally modulated laser pulse with non-uniform time intervals between the adjacent micro-peaks, which means that there is a chirp in the modulation frequency, and this chirp can be continuously tuned. The interaction is made to occur between an electron beam and the modulated laser pulse in a modulator (an undulator tuned at the laser wavelength), then terahertz synchrotron radiation with the same spectrum characteristics as the modulated laser will be generated when the electron beam passes through the following bending magnet. We expect that this method will open a new way for the coherent control of quantum systems in the terahertz regime.

7 citations

Journal ArticleDOI
TL;DR: In this article, a scheme to generate coherent terahertz (THz) radiation carrying orbital angular momentum (OAM) through down-frequency conversion of optical lasers and higher order mode coupling is proposed and analyzed.
Abstract: A scheme to generate coherent terahertz (THz) radiation carrying orbital angular momentum (OAM) through down-frequency conversion of optical lasers and higher order mode coupling is proposed and analyzed. Based on the laser–electron interaction in the undulator under a linear regime, the scheme utilizes dual-frequency lasers resonating at the harmonics of two consecutive undulators and a dispersion section to impose a THz helical microbunching in the electron beam. By choosing appropriate parameters of lasers and dispersion section, the density modulation can be down-converted to a THz spectral-domain and the central frequency can be extensively tuned together with the helical mode number. Then, the helically microbunched beam can be used as a source of THz OAM radiation in a downstream radiator. We expect that the intense vortex beam in the terahertz band will bring new opportunities for the research of quantum topological materials.

4 citations

Journal ArticleDOI
TL;DR: In this article, a photoelectron beam is generated from the cathode under the illumination of a driving laser pulse in the electron gun, which is subsequently microbunched to optical wavelength scale by the field of a synchronized radially polarized laser (RPL) pulse.
Abstract: The interaction of light and electrons has been one of the important frontiers for generating ultrashort electron pulses in free-electron lasers, ultrafast science, and dynamical analysis of matter. However, the generation of a relativistic attosecond electron beam remains a challenge. In a photocathode radio-frequency (rf) gun, this work identifies a regime for obtaining an isolated or a train of relativistic attosecond electron pulses. A photoelectron beam is generated from the cathode under the illumination of a driving laser pulse in the electron gun, which is subsequently microbunched to optical wavelength scale by the field of a synchronized radially polarized laser (RPL) pulse that is focused near the cathode surface. The rf field in the gun cavity simultaneously accelerates the electron pulse to several MeV. The rf field causes a velocity differential inside the electron beam as it passes into the region near the focal point of the RPL (microbunching is processed), and the microbunch at the head is substantially faster than that at the tail. Using this knowledge, the spacing between consecutive microbunches, referred to as bunch spacing, may be controlled across a wide range by regulating the velocity difference, which can be accomplished by tuning the phase and amplitude of the rf field. Numerical simulations show that a train of attosecond bunches with tunable bunch spacing can be generated using realistic laser parameters corresponding to current GW-power-level laser systems, and an isolated attosecond pulse can be obtained when the driving laser pulse is about 50 fs. This regime may result in opportunities in ultrafast electron diffraction and microscopy, free-electron lasers, and other applications that require high-energy electrons with the temporal structure of single-cycle light.

4 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this paper, the authors show that terahertz (1 THz = 10$12}$ Hz) electromagnetic pulses allow coherent navigation of spins over a potential barrier and reveal the corresponding temporal and spectral fingerprints.
Abstract: Future information technology demands ultimately fast, low-loss quantum control. Intense light fields have facilitated important milestones, such as inducing novel states of matter, accelerating electrons ballistically, or coherently flipping the valley pseudospin. These dynamics leave unique signatures, such as characteristic bandgaps or high-order harmonic radiation. The fastest and least dissipative way of switching the technologically most important quantum attribute - the spin - between two states separated by a potential barrier is to trigger an all-coherent precession. Pioneering experiments and theory with picosecond electric and magnetic fields have suggested this possibility, yet observing the actual dynamics has remained out of reach. Here, we show that terahertz (1 THz = 10$^{12}$ Hz) electromagnetic pulses allow coherent navigation of spins over a potential barrier and we reveal the corresponding temporal and spectral fingerprints. This goal is achieved by coupling spins in antiferromagnetic TmFeO$_{3}$ with the locally enhanced THz electric field of custom-tailored antennas. Within their duration of 1 ps, the intense THz pulses abruptly change the magnetic anisotropy and trigger a large-amplitude ballistic spin motion. A characteristic phase flip, an asymmetric splitting of the magnon resonance, and a long-lived offset of the Faraday signal are hallmarks of coherent spin switching into adjacent potential minima, in agreement with a numerical simulation. The switchable spin states can be selected by an external magnetic bias. The low dissipation and the antenna's sub-wavelength spatial definition could facilitate scalable spin devices operating at THz rates.

92 citations

Journal ArticleDOI
TL;DR: In this article, the basic principle of free-electron laser (FEL) was discussed, and the techniques for realizing fully coherent FELs were discussed as well as the development of FEL facilities in China.

78 citations

Journal ArticleDOI
TL;DR: In this article, the main processes for XFELO design, and parameter optimization of the undulator, X-ray cavity, and electron beam are described, which can be combined with the GENESIS and OPC codes for the numerical simulations of the X FELO.
Abstract: The Shanghai Coherent Light Facility (SCLF) is a quasi-continuous wave hard X-ray free electron laser facility, which is currently under construction. Due to the high repetition rate and high-quality electron beams, it is straightforward to consider X-ray free electron laser oscillator (XFELO) operation for the SCLF. In this paper, the main processes for XFELO design, and parameter optimization of the undulator, X-ray cavity, and electron beam are described. A three-dimensional X-ray crystal Bragg diffraction code, named BRIGHT, was introduced for the first time, which can be combined with the GENESIS and OPC codes for the numerical simulations of the XFELO. The performance of the XFELO of the SCLF is investigated and optimized by theoretical analysis and numerical simulation.

21 citations

Journal Article
TL;DR: In this paper, preliminary results of the Chirped Pulse Amplification (CPA) of the HGHG radiation were presented. But the results were limited to the DUV-FEL facility.

12 citations

Journal ArticleDOI
TL;DR: In this paper , the authors review the existing approaches for vortex and vector beam shaping and generation in the terahertz frequency range and propose a unified concept for constructing passive shapers of such beams from the existing component base.
Abstract: Design of broadband terahertz vector and vortex beams: I. Review of materials and Components. Light: Abstract In this paper, we review the existing approaches for vortex and vector beam shaping and generation in the terahertz frequency range. The particular focus of this review is on the possibility of homogeneous topological charge formation in the ultra-wide spectral interval inherent to ultrashort terahertz pulses. We review the available materials and components, analyse proposed and potentially possible solutions for broadband terahertz vortex and vector beam shaping, compare all developed approaches, and put forward a unified concept for constructing passive shapers of such beams from the existing component base.

9 citations