An iterative physical optics(IPO) model is proposed to solve extra large scale electric electromagnetic(EM) scattering from randomly rough surfaces. In order to accelerate the convergence of the IPO model, the for...An iterative physical optics(IPO) model is proposed to solve extra large scale electric electromagnetic(EM) scattering from randomly rough surfaces. In order to accelerate the convergence of the IPO model, the forward-backward methodology and its modification with underrelaxation iteration are developed to simulate the rough surface scattering; the local iteration methodology and the fast far field approximation(Fa FFA) in the matrix-vector product are proposed to reduce greatly the computational complexity. These techniques make Monte Carlo simulations possible. Thus, the average Doppler spectra of backscattered signals obtained from the simulations are compared for different incident angles and sea states. In particular, the simulations show a broadening of the Doppler spectra for a more complicated sea state at a low grazing angle(LGA).展开更多
In this study, we designed and fabricated optical materials consisting of alternating ITO and Ag layers. This approach is considered to be a promising way to obtain a light-weight, ultrathin and transparent shielding ...In this study, we designed and fabricated optical materials consisting of alternating ITO and Ag layers. This approach is considered to be a promising way to obtain a light-weight, ultrathin and transparent shielding medium, which not only transmits visible light but also inhibits the transmission of microwaves, despite the fact that the total thickness of the Ag film is much larger than the skin depth in the visible range and less than that in the microwave region. Theoretical results suggest that a high dielectric/metal thickness ratio can enhance the broadband and improve the transmittance in the optical range. Accordingly, the central wavelength was found to be red-shifted with increasing dielectric/metal thickness ratio. A physical mechanism behind the controlling transmission of visible light is also proposed. Meanwhile, the electromagnetic shielding effectiveness of the prepared structures was found to exceed 40 dB in the range from 0.1 GHz to 18 GHz, even reaching up to 70 dB at 0.1 GHz, which is far higher than that of a single ITO film of the same thickness.展开更多
A transverse-longitudinal cross-spectral density matrix (TLCSDM) of partially coherent electromagnetic beams is proposed. It can extend the traditional Stokes parameters and polarization singularities from the parax...A transverse-longitudinal cross-spectral density matrix (TLCSDM) of partially coherent electromagnetic beams is proposed. It can extend the traditional Stokes parameters and polarization singularities from the paraxial field to the more general situation. The impact produced by the atmospheric turbulence on polarization singularities of the partially coherent electromagnetic vortex beams is analyzed with the TLCSDM.展开更多
A Babinet-inverted optical nanoantenna analogue of electromagnetically induced transparency based on the coupling between two magnetic dipole antennas and a magnetic octupole antenna in a Au film waveguide is demonstr...A Babinet-inverted optical nanoantenna analogue of electromagnetically induced transparency based on the coupling between two magnetic dipole antennas and a magnetic octupole antenna in a Au film waveguide is demonstrated. Simulation results indicate that a pronounced elimination occurs in the radiating spectrum due to the coupling-induced radiation suppression. A two-oscillator electromagnetically induced transparency model is used to describe the antenna. The coupling coefficient between the magnetic dipole antennas and the magnetic octupole antenna is calculated using the model and is found to decline exponentially with the increase of the distance between them. Such an antenna can be directly integrated with optical waveguides or transmission lines,thus is of fundamental significance for the applications in nano-optics, such as the optical device miniaturizations and photonic circuit integrations.展开更多
The generation and observation of coherent THz synchrotron radiation from femtosecond electron bunches in the Shanghai Institute of Applied Physics femtosecond accelerator device is reported. We describe the experimen...The generation and observation of coherent THz synchrotron radiation from femtosecond electron bunches in the Shanghai Institute of Applied Physics femtosecond accelerator device is reported. We describe the experiment setup and present the first result of THz radiation properties such as power and spectrum.展开更多
Two dimensional particle-in-cell simulations are taken to study the interaction of a circularly polarized laser pulse with a nano-scale micro-structured target. The protons which are doped in the rear side of the targ...Two dimensional particle-in-cell simulations are taken to study the interaction of a circularly polarized laser pulse with a nano-scale micro-structured target. The protons which are doped in the rear side of the target experience the electrostatic fields caused by both the radiation pressure driven shock and the target normal sheath at the rear side of the target. A quasimonoenergetic proton bunch with central energy of about 11MeV and energy spread of ∆ ε/ε about 0.18 is achieved by using a 3.45×1019 W/cm2, 66fs laser pulse. A comparison with the case of linearly polarized laser pulse and the same target condition is considered.展开更多
基金supported by the National Natural Science Foundation of China(61372033)
文摘An iterative physical optics(IPO) model is proposed to solve extra large scale electric electromagnetic(EM) scattering from randomly rough surfaces. In order to accelerate the convergence of the IPO model, the forward-backward methodology and its modification with underrelaxation iteration are developed to simulate the rough surface scattering; the local iteration methodology and the fast far field approximation(Fa FFA) in the matrix-vector product are proposed to reduce greatly the computational complexity. These techniques make Monte Carlo simulations possible. Thus, the average Doppler spectra of backscattered signals obtained from the simulations are compared for different incident angles and sea states. In particular, the simulations show a broadening of the Doppler spectra for a more complicated sea state at a low grazing angle(LGA).
基金Project supported by the International Science&Technology Cooperation Program of China(Grant No.2014DFR10020)the Science Foundation of Shanxi Province,China(Grant Nos.201701D121050 and 201701D121007)
文摘In this study, we designed and fabricated optical materials consisting of alternating ITO and Ag layers. This approach is considered to be a promising way to obtain a light-weight, ultrathin and transparent shielding medium, which not only transmits visible light but also inhibits the transmission of microwaves, despite the fact that the total thickness of the Ag film is much larger than the skin depth in the visible range and less than that in the microwave region. Theoretical results suggest that a high dielectric/metal thickness ratio can enhance the broadband and improve the transmittance in the optical range. Accordingly, the central wavelength was found to be red-shifted with increasing dielectric/metal thickness ratio. A physical mechanism behind the controlling transmission of visible light is also proposed. Meanwhile, the electromagnetic shielding effectiveness of the prepared structures was found to exceed 40 dB in the range from 0.1 GHz to 18 GHz, even reaching up to 70 dB at 0.1 GHz, which is far higher than that of a single ITO film of the same thickness.
基金Supported by the Open Foundation of the Sate Key Laboratory of Optical Technologies for Micro-Fabrication and Micro- Engineering, Chinese Academy of Sciences, and the China Postdoctoral Science Foundation under Grant No 2009450159.
文摘A transverse-longitudinal cross-spectral density matrix (TLCSDM) of partially coherent electromagnetic beams is proposed. It can extend the traditional Stokes parameters and polarization singularities from the paraxial field to the more general situation. The impact produced by the atmospheric turbulence on polarization singularities of the partially coherent electromagnetic vortex beams is analyzed with the TLCSDM.
基金Supported by the National Key Research and Development Program of China under Grant No 2016YFA0301300the National Natural Science Foundation of China under Grant Nos 11374041,11574035 and 11404030the State Key Laboratory of Information Photonics and Optical Communications
文摘A Babinet-inverted optical nanoantenna analogue of electromagnetically induced transparency based on the coupling between two magnetic dipole antennas and a magnetic octupole antenna in a Au film waveguide is demonstrated. Simulation results indicate that a pronounced elimination occurs in the radiating spectrum due to the coupling-induced radiation suppression. A two-oscillator electromagnetically induced transparency model is used to describe the antenna. The coupling coefficient between the magnetic dipole antennas and the magnetic octupole antenna is calculated using the model and is found to decline exponentially with the increase of the distance between them. Such an antenna can be directly integrated with optical waveguides or transmission lines,thus is of fundamental significance for the applications in nano-optics, such as the optical device miniaturizations and photonic circuit integrations.
文摘The generation and observation of coherent THz synchrotron radiation from femtosecond electron bunches in the Shanghai Institute of Applied Physics femtosecond accelerator device is reported. We describe the experiment setup and present the first result of THz radiation properties such as power and spectrum.
基金Supported by the National Key Basic Research Program of China under Grant No 2006CB806004, the National Natural Science Foundation of China under Grant Nos 10675155 and 10834008, Scientific Research Foundation for Awarder of Excellent Doctor Thesis, and President Award of Chinese Academy of Sciences (No 0801051-X00).
文摘Two dimensional particle-in-cell simulations are taken to study the interaction of a circularly polarized laser pulse with a nano-scale micro-structured target. The protons which are doped in the rear side of the target experience the electrostatic fields caused by both the radiation pressure driven shock and the target normal sheath at the rear side of the target. A quasimonoenergetic proton bunch with central energy of about 11MeV and energy spread of ∆ ε/ε about 0.18 is achieved by using a 3.45×1019 W/cm2, 66fs laser pulse. A comparison with the case of linearly polarized laser pulse and the same target condition is considered.