To study ultrafast processes at the sub-picosecond level, novel methods based on coherent harmonic generation technologies have been proposed to generate ultrashort radiation pulses in existing ring-based light source...To study ultrafast processes at the sub-picosecond level, novel methods based on coherent harmonic generation technologies have been proposed to generate ultrashort radiation pulses in existing ring-based light sources. Using the High Energy Photon Source as an example, we numerically test the feasibility of implementing one coherent harmonic generation technology, i.e.,the echo-enabled harmonic generation(EEHG) scheme, in a diffraction-limited storage ring(DLSR). Two different EEHG element layouts are considered, and the effect of the EEHG process on the electron beam quality is also analyzed. Studies suggest that soft X-ray pulses, with pulse lengths of a few femtoseconds and peak powers of up to1 MW, can be generated by using the EEHG scheme, while causing little perturbation to the regular operation of a DLSR.展开更多
To date, two-color pulses are widely used in pump–probe experiments. For a ring-based light source, the power of the spontaneous radiation fluctuates randomly in the longitudinal direction. It is difficult to produce...To date, two-color pulses are widely used in pump–probe experiments. For a ring-based light source, the power of the spontaneous radiation fluctuates randomly in the longitudinal direction. It is difficult to produce twocolor double pulses by optical methods. In this paper, we introduce a method based on the echo-enabled harmonic generation scheme that generates two-color pulses in a storage ring light source. By adopting crossed undulators and a phase shifter, the polarization of the two-color pulses can be easily switched. A numerical simulation based on a diffraction-limited storage ring, the Hefei Advanced Light Source, suggests that the time delay and spectral separation of the two pulses can be adjusted linearly by changing the pulse duration and chirp parameters of the seed laser. A circular polarization degree above 80% could be achieved.展开更多
X-ray frequency combs(XFCs)are of great interest in many scientific research areas.In this study,we investigate the generation of high-power tunable XFCs at the Shanghai soft X-ray Free-Electron Laser facility(SXFEL)....X-ray frequency combs(XFCs)are of great interest in many scientific research areas.In this study,we investigate the generation of high-power tunable XFCs at the Shanghai soft X-ray Free-Electron Laser facility(SXFEL).To achieve this,a chirped frequency-beating laser is employed as the seed laser for echo-enabled harmonic generation of free-electron lasers.This approach enables the formation of an initial bunching of combs and ultimately facilitates the generation of XFCs under optimized conditions.We provide an optical design for the chirped frequency-beating seed laser system and outline a method to optimize and set the key parameters that meets the critical requirements for generating continuously tunable XFCs.Three-dimensional simulations using realistic parameters of the SXFEL demonstrate that it is possible to produce XFCs with peak power reaching 1.5 GW,central photon energy at the carbon K edge(~284 eV)and tunable repetition frequencies ranging from 7 to 12 THz.Our proposal opens up new possibilities for resonant inelastic X-ray scattering experiments at X-ray free-electron laser facilities.展开更多
This paper reviews the development of X-ray free-electron lasers ( XFELs) . With the unprecedented characteristics of flexible wavelength tunability ,high brightness ,ultrashort pulse duration ,and fully transverse co...This paper reviews the development of X-ray free-electron lasers ( XFELs) . With the unprecedented characteristics of flexible wavelength tunability ,high brightness ,ultrashort pulse duration ,and fully transverse coherence ,these accelerator-based X-ray light sources will open newfields in physics ,chemistry , material ,and life sciences . Based on the present status of XFELs in the worldwide context ,the future directions are analyzed .A brief summary of the developments of free-electron lasers (FELs) in China is given .展开更多
基金supported by National Natural Science Foundation of China(No.11475202,11405187)the Youth Innovation Association of Chinese Academy of SciencesKey Research Program of Frontier Sciences,CAS(No.QYZDJ-SSW-SLH001)
文摘To study ultrafast processes at the sub-picosecond level, novel methods based on coherent harmonic generation technologies have been proposed to generate ultrashort radiation pulses in existing ring-based light sources. Using the High Energy Photon Source as an example, we numerically test the feasibility of implementing one coherent harmonic generation technology, i.e.,the echo-enabled harmonic generation(EEHG) scheme, in a diffraction-limited storage ring(DLSR). Two different EEHG element layouts are considered, and the effect of the EEHG process on the electron beam quality is also analyzed. Studies suggest that soft X-ray pulses, with pulse lengths of a few femtoseconds and peak powers of up to1 MW, can be generated by using the EEHG scheme, while causing little perturbation to the regular operation of a DLSR.
基金supported by the National Natural Science Foundation of China(Nos.11475202,11405187)Youth Innovation Association of Chinese Academy of Sciences,and Bureau of Frontier Sciences and Education,Chinese Academy of Sciences(No.QYZDJ-SSWSLH001)National Key R&D Program of China(No.2016YFA0401900)
文摘To date, two-color pulses are widely used in pump–probe experiments. For a ring-based light source, the power of the spontaneous radiation fluctuates randomly in the longitudinal direction. It is difficult to produce twocolor double pulses by optical methods. In this paper, we introduce a method based on the echo-enabled harmonic generation scheme that generates two-color pulses in a storage ring light source. By adopting crossed undulators and a phase shifter, the polarization of the two-color pulses can be easily switched. A numerical simulation based on a diffraction-limited storage ring, the Hefei Advanced Light Source, suggests that the time delay and spectral separation of the two pulses can be adjusted linearly by changing the pulse duration and chirp parameters of the seed laser. A circular polarization degree above 80% could be achieved.
基金supported by the National Natural Science Foundation of China(No.12122514)Zhangjiang Laboratory,Project for Young Scientists in Basic Research of the Chinese Academy of Sciences(No.YSBR-091)the Strategy Priority Research Program of the Chinese Academy of Sciences(No.XDB0530300)。
文摘X-ray frequency combs(XFCs)are of great interest in many scientific research areas.In this study,we investigate the generation of high-power tunable XFCs at the Shanghai soft X-ray Free-Electron Laser facility(SXFEL).To achieve this,a chirped frequency-beating laser is employed as the seed laser for echo-enabled harmonic generation of free-electron lasers.This approach enables the formation of an initial bunching of combs and ultimately facilitates the generation of XFCs under optimized conditions.We provide an optical design for the chirped frequency-beating seed laser system and outline a method to optimize and set the key parameters that meets the critical requirements for generating continuously tunable XFCs.Three-dimensional simulations using realistic parameters of the SXFEL demonstrate that it is possible to produce XFCs with peak power reaching 1.5 GW,central photon energy at the carbon K edge(~284 eV)and tunable repetition frequencies ranging from 7 to 12 THz.Our proposal opens up new possibilities for resonant inelastic X-ray scattering experiments at X-ray free-electron laser facilities.
文摘This paper reviews the development of X-ray free-electron lasers ( XFELs) . With the unprecedented characteristics of flexible wavelength tunability ,high brightness ,ultrashort pulse duration ,and fully transverse coherence ,these accelerator-based X-ray light sources will open newfields in physics ,chemistry , material ,and life sciences . Based on the present status of XFELs in the worldwide context ,the future directions are analyzed .A brief summary of the developments of free-electron lasers (FELs) in China is given .
