Enhanced diffraction radiation from two dimensional periodical structure

Stronger surface plasmon polaritons (SPPs) enhanced diffraction radiation will be obtained on rectangular metallic bigrating comparing to one dimensional grating excited by a uniformly parallel moving electron beam, the stronger enhancement comes from the interaction effect of two SPPs excited simultaneously along the orthogonal period structure of rectangular metallic bigrating. Based on the advantage of rectangular bigrating, we presented and explored a novel metal film attached two-dimensional periodical lattice structure by reducing the thickness of the bigrating substrate to tens of nanometers. In this structure, with the excitation of uniform electron beam moving above the metal film surface, SPPs are firstly excited on the metal film, which will couple with the electromagnetic fields in the two-dimensional periodical lattice, and then transformed into enhanced radiation wave by diffracting of the rectangular lattice. The radiation power can reach 2.7 times that of the bigrating with dramatically decreased exciting beam energy, the fields can radiate to the whole space comparing to only the upper half space for the bigrating. To obtain better radiation behavior, double metal films sandwiched two-dimensional periodical lattice structure is proposed, which provides radiation power over 10 times that of bigrating. The results will be beneficial to electromagnetic radiation source based on SPPs in ultraviolet region.