Calculations of the TE10 tapered waveguide, which will be used in the 4.6 GHz lower hybrid current drive （LHCD） launcher on the EAST, are presented. The calculations are performed in two ways, namely by directly sol...Calculations of the TE10 tapered waveguide, which will be used in the 4.6 GHz lower hybrid current drive （LHCD） launcher on the EAST, are presented. The calculations are performed in two ways, namely by directly solving the classical coupling wave equations, and by using the simulation code of the high frequency structure simulator （HFSS）. According to the calculations, the voltage standing wave ratio （VSWR） of the designed tapered waveguide can be less than 1.01 within a bandwidth of ±100 MHz.展开更多
Based on a modified coupled wave theory of Kogelnik, we have studied the diffraction of an ultrashort pulsed beam with an arbitrary polarization state from a volume holographic grating in photorefractive LiNbO3 crysta...Based on a modified coupled wave theory of Kogelnik, we have studied the diffraction of an ultrashort pulsed beam with an arbitrary polarization state from a volume holographic grating in photorefractive LiNbO3 crystals. The results indicate that the diffracted intensity distributions in the spectral and temporal domains and the diffraction efficiency of the grating are both changed by the polarization state and spectral bandwidth of the input pulsed beam. A method is given of choosing the grating parameters and input conditions to obtain a large variation range of the spectral bandwidth of the diffracted pulsed beam with an appropriate diffraction efficiency. Our study presents a possibility of using a volume holographic grating recorded in anisotropic materials to shape a broadband ultrashort pulsed beam by modulating its polarization state.展开更多
文摘Calculations of the TE10 tapered waveguide, which will be used in the 4.6 GHz lower hybrid current drive （LHCD） launcher on the EAST, are presented. The calculations are performed in two ways, namely by directly solving the classical coupling wave equations, and by using the simulation code of the high frequency structure simulator （HFSS）. According to the calculations, the voltage standing wave ratio （VSWR） of the designed tapered waveguide can be less than 1.01 within a bandwidth of ±100 MHz.
基金Project supported by the State Key Development Program for Basic Research of China （Grant No 2002CCA03500）, and the National Natural Science Foundation of China （Grant No 60177016）.
文摘Based on a modified coupled wave theory of Kogelnik, we have studied the diffraction of an ultrashort pulsed beam with an arbitrary polarization state from a volume holographic grating in photorefractive LiNbO3 crystals. The results indicate that the diffracted intensity distributions in the spectral and temporal domains and the diffraction efficiency of the grating are both changed by the polarization state and spectral bandwidth of the input pulsed beam. A method is given of choosing the grating parameters and input conditions to obtain a large variation range of the spectral bandwidth of the diffracted pulsed beam with an appropriate diffraction efficiency. Our study presents a possibility of using a volume holographic grating recorded in anisotropic materials to shape a broadband ultrashort pulsed beam by modulating its polarization state.
