Vortex Smith-Purcell radiation generation with holographic grating

• 作者: FANG LIU KAIYU CUI MENGXUAN WANG WEI ZHANG XUE FENG YIDONG HUANG YUECHAI LIN
• 来源期刊: 光子学研究:英文版
• 学科: 工学
• 关键词: HOLOGRAPHIC WAVE VORTEX
• 年，卷（期）: 2020,（8）
• 页码范围: 1309-1315
• 页数: 7页
• 分类号: TN9

摘要

Smith–Purcell radiation(SPR)is the electromagnetic wave generated by free electrons passing above a diffraction grating,and it has played an important role in free-electron light sources and particle accelerators.Orbital angular momentum(OAM)is a new degree of freedom that can significantly promote the capacity of information carried by an electro-magnetic beam.In this paper,we propose an integrable method for generating vortex Smith–Purcell radiation(VSPR),namely,SPR carrying OAM,by having free-electron bunches pass on planar holographic gratings.VSPRs generated by different electron energies,with different topological charges of the OAM,radiation angles,and frequencies are demonstrated numerically.It is also found that,for high-order radiation,the topological charge of the OAM wave will be multiplied by the radiation order.This work introduces a new way to generate SPR with OAM and provides a method to achieve an integratable and tunable free-electron OAM wave source at different frequency regions.