부산대학교 도서관

The generation of coherent and high-mode purity vortex beams carrying orbital angular momentum can be achieved through Vortex Smith-Purcell radiation from chiral plasmons. However, to selectively excite the chiral plasmons, it is necessary to generate an electron beam with a specific rotational symmetry. In this study, we propose a scheme for an electron gun that can emit an electron beam with transverse rotational symmetry by customizing the emission region of the cathode. The trajectories of the electron beams from the numerical simulations illustrate the feasibility of the proposed scheme. By employing the customized beam, plasmons with a specific topological charge can be alternatively excited and diffracted into coherent vortex free-electron radiations, thereby enabling the development of multi-mode communications and chiral detections in the terahertz band.