A Terahertz Vortex Beam Emitter With Tunable Topological Charge and Harmonic Excitation

Terahertz (THz) vortex beams carrying orbital angular momentum (OAM) with high purity and tunable topological charge (TC) will undoubtedly bring extraordinary capacities for advanced imaging or communication systems. We propose a convenient efficient method to generate broadband beam that is excited by superradiant Smith-Purcell radiation (SSPR) on helical grating. This scheme fully explores the advantages of natural evanescent wave carried electron Bloch's theorem regulated periodic An explicit relation established between index spatial harmonic grating beam. The energy in SSPR can be customized ignite specific harmonics manipulate OAM beam, accordingly. separated region also promises spectrum. excitation reduces communality wavelength device size alleviates difficulty fabrication THz band. proposed not only handily scaled microwave mid-infrared regions, but possibilities applications based compact sources.