Field Distribution Analysis of Vortex Surface Plasmons

The generation of coherent and high-purity vortex beams with diverse orbital angular momentum (OAM) is achievable via Vortex Smith-Purcell radiation (SPR) mediated by vortex surface plasmons supported by helical gratings. Nevertheless, the field distribution of vortex surface plasmons remains underexplored. This study presents a comprehensive analytical investigation into the field distribution of vortex surface plasmons. By analyzing the field distribution corresponding to various topological charges, we aim to elucidate their intrinsic relationship, enhancing the practical deployment of vortex surface plasmons. This theoretical framework will facilitate the precise excitation of surface plasmons with designated topological charges and their subsequent diffraction into coherent vortex free-electron radiation, thereby advancing high-capacity communication, quantum information processing, and other cutting-edge applications.