In classical linear optics,when light shines upon a grating in the normal configuration where the incident plane of light is perpendicular to the optical axis of the grating,ordinary Bragg diffraction will occur.Howev...In classical linear optics,when light shines upon a grating in the normal configuration where the incident plane of light is perpendicular to the optical axis of the grating,ordinary Bragg diffraction will occur.However,when light is incident in the general conical configuration where the incident plane of light is oblique to the optical axis of the grating,the Bragg diffraction becomes much more complicated.What happens to the nonlinear diffraction of a laser beam by a nonlinear grating?In this Letter,we wish to answer this interesting and fundamental question in the realm of nonlinear optics.We shine a Ti:sapphire femtosecond pulse laser beam(with a central wavelength at 800 nm)upon a periodically poled lithium niobate(PPLN)thin plate nonlinear grating and systematically investigate the Raman-Nath nonlinear diffraction(NRND)pattern of a second-harmonic generation(SHG)laser beam in various“conical”(or off-plane)incidence configurations characterized by both the polar angleαand azimuthal angleφ.By analyzing the diffraction characteristic and uncovering the underlying mechanisms of conical NRND nonlinear diffraction,we have provided a comprehensive understanding of its spatial behavior.The study of conical nonlinear diffraction enriches the understanding of the complicated interaction between the pump laser beam and the structured nonlinear medium and broadens the arena of nonlinear optics.展开更多
The Chinese Academy of Engineering Physics Terahertz Free Electron Laser Facility(CAEP THz FEL,CTFEL)is the only high-average power free electron laser terahertz source based on superconducting accelerators in China.T...The Chinese Academy of Engineering Physics Terahertz Free Electron Laser Facility(CAEP THz FEL,CTFEL)is the only high-average power free electron laser terahertz source based on superconducting accelerators in China.The update of the CTFEL is now undergoing and will expand the frequency range from 0.1–4.2 THz to 0.1–125 THz.Two experimental stations for material spectroscopy and biomedicine will be built.A high harmonic generation(HHG)lightsource based beamline at the material spectroscopy experimental station for time-resolved angle-resolved photoemission spectroscopy(ARPES)research will be constructed and the optical design is presented.The HHG lightsource covers the extreme ultraviolet(XUV)photon energy range of 20–50 eV.A Czerny–Turner monochromator with two plane gratings worked in conical diffraction configuration is employed to maintain the transmission efficiency and preserve the pulse time duration.The calculated beamline transmission efficiency is better than 5%in the whole photon energy range.To our knowledge,this is the first time in China to combine THz-infrared FEL with HHG light source,and this experimental station will be a powerful and effective instrument that will give new research opportunities in the future for users doing research on the dynamic evolution of the excited electron band structure of a material’s surface.展开更多
We accomplish a laboratory facility for producing a femtosecond XUV coherent monochromatic radiation with a broad tunable spectral range of 20 eV-75 eV. It is based on spectral selected single-order harmonics from int...We accomplish a laboratory facility for producing a femtosecond XUV coherent monochromatic radiation with a broad tunable spectral range of 20 eV-75 eV. It is based on spectral selected single-order harmonics from intense laser driven high harmonic generation in gas phase. The time preserving for the selected harmonic radiation is achieved by a Czerny-Turner type monochromator designed with a conical diffraction grating mount for minimizing the time broadening caused by grating diffraction and keeping a relatively high diffraction efficiency. Our measurement shows that the photon flux of the 23-order harmonic（H23） centered at 35.7 eV is 1×10~9 photons/s approximately with a resolving power E/？E ≈ 36.This source provides an ultrashort tunable monochromatic XUV beam for ultrafast studies of electronic and structural dynamics in a large variety of matters.展开更多
基金supported by the Science and Technology Project of Guangdong(No.2020B010190001)the National Natural Science Foundation of China(No.12434016)the National Funded Postdoctoral Researcher Program(No.GZB20240785)。
文摘In classical linear optics,when light shines upon a grating in the normal configuration where the incident plane of light is perpendicular to the optical axis of the grating,ordinary Bragg diffraction will occur.However,when light is incident in the general conical configuration where the incident plane of light is oblique to the optical axis of the grating,the Bragg diffraction becomes much more complicated.What happens to the nonlinear diffraction of a laser beam by a nonlinear grating?In this Letter,we wish to answer this interesting and fundamental question in the realm of nonlinear optics.We shine a Ti:sapphire femtosecond pulse laser beam(with a central wavelength at 800 nm)upon a periodically poled lithium niobate(PPLN)thin plate nonlinear grating and systematically investigate the Raman-Nath nonlinear diffraction(NRND)pattern of a second-harmonic generation(SHG)laser beam in various“conical”(or off-plane)incidence configurations characterized by both the polar angleαand azimuthal angleφ.By analyzing the diffraction characteristic and uncovering the underlying mechanisms of conical NRND nonlinear diffraction,we have provided a comprehensive understanding of its spatial behavior.The study of conical nonlinear diffraction enriches the understanding of the complicated interaction between the pump laser beam and the structured nonlinear medium and broadens the arena of nonlinear optics.
基金supported by Major Instrument Projects of Sichuan Province.
文摘The Chinese Academy of Engineering Physics Terahertz Free Electron Laser Facility(CAEP THz FEL,CTFEL)is the only high-average power free electron laser terahertz source based on superconducting accelerators in China.The update of the CTFEL is now undergoing and will expand the frequency range from 0.1–4.2 THz to 0.1–125 THz.Two experimental stations for material spectroscopy and biomedicine will be built.A high harmonic generation(HHG)lightsource based beamline at the material spectroscopy experimental station for time-resolved angle-resolved photoemission spectroscopy(ARPES)research will be constructed and the optical design is presented.The HHG lightsource covers the extreme ultraviolet(XUV)photon energy range of 20–50 eV.A Czerny–Turner monochromator with two plane gratings worked in conical diffraction configuration is employed to maintain the transmission efficiency and preserve the pulse time duration.The calculated beamline transmission efficiency is better than 5%in the whole photon energy range.To our knowledge,this is the first time in China to combine THz-infrared FEL with HHG light source,and this experimental station will be a powerful and effective instrument that will give new research opportunities in the future for users doing research on the dynamic evolution of the excited electron band structure of a material’s surface.
基金Project supported by the National Natural Science Foundation of China(Grants Nos.11627807,11127403,and 11474130)the National Basic Research Program of China(Grant No.2013CB922200)the Natural Science Foundation of Jilin Province of China(Grant No.20160101332JC)
文摘We accomplish a laboratory facility for producing a femtosecond XUV coherent monochromatic radiation with a broad tunable spectral range of 20 eV-75 eV. It is based on spectral selected single-order harmonics from intense laser driven high harmonic generation in gas phase. The time preserving for the selected harmonic radiation is achieved by a Czerny-Turner type monochromator designed with a conical diffraction grating mount for minimizing the time broadening caused by grating diffraction and keeping a relatively high diffraction efficiency. Our measurement shows that the photon flux of the 23-order harmonic（H23） centered at 35.7 eV is 1×10~9 photons/s approximately with a resolving power E/？E ≈ 36.This source provides an ultrashort tunable monochromatic XUV beam for ultrafast studies of electronic and structural dynamics in a large variety of matters.
