Enhance the terahertz Smith-Purcell superradiant radiation by using dielectric loaded grating

Abstract

A dielectric loaded grating (DLG) for terahertz Smith-Purcell (SP) device is proposed to enhance the radiation intensity. By using the theoretical analysis and particle-in-cell simulations, the dispersion characteristics and SP superradiant radiation are investigated. Compared with the general metal grating, the usage of DLG can improve the magnitude of electric field and, consequently, strengthen the interaction of the evanescent wave with electron beam, which can improve the growth rate, enhance the SP superradiant radiation, and lower the start current for the operation of SP free-electron laser.

Space‐Time Wave Packets from Smith‐Purcell Radiation

“…[ 104 , 105 ] While the group velocity of space‐time wave packet is unaffected by the grating geometry and material, the spectral distribution of Smith‐Purcell radiation can be controlled using multiple grating layers of different materials, periodicities, and thicknesses. For instance, the intensity of Smith‐Purcell radiation can be enhanced using dielectric loaded gratings, [ 106 , 107 , 108 ] and Smith‐Purcell radiation can be simultaneously generated at multiple frequencies (for a given propagation direction) using a super grating structure with two grating layers of different periodicity. [ 109 ] Hence, the design of multilayer gratings offers new ways of controlling the field profiles of space‐time wave packets generated by Smith‐Purcell radiation.…”

Smith–Purcell radiation improved by multi-grating structure

“…[3,4] The SPR is a wide spectrum electromagnetic radiation, [5,6] which has been obtained from the metal chains, [7] sub-wavelength hole array, [8,9] metamaterials [10][11][12] and photonic crystal, [13][14][15][16][17][18] etc. The physical mechanisms of superradiate SPR, [19,20] surface plasmon enhanced SPR [8][9][10] and compression SPR [8] have been found and analyzed by researchers.…”