Smith-Purcell Radiation Enhanced by Localized Surface Plasmons Excited by Free Electrons

The interaction of free electrons with metallic nanostructures has long been a subject of interest due to its ability to generate surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs). In this study, we investigate the enhanced Smith-Purcell Radiation (SPR) resulting from LSPs excitation by free electrons on gold gratings. Through theoretical calculations and electromagnetic simulations, we demonstrate that LSPs can significantly enhance SPR when their dispersion relation aligns with the fast-wave zone of the grating period structure. The optimal parameters for LSP-enhanced SPR were determined, and the results were experimentally verified using a self-modified scanning electron microscope (SEM) and spectrometer system. Our findings provide insights into the potential of using free electron excitation in metal gratings to enhance light-matter interactions, with applications in photonics and materials science.