Terahertz Surface Plasmon Generation from Laser Interaction with a Magnetized Metallic Surface

The excitation of surface plasma waves (SPWs) by the interaction of lasers with a metal surface can generate terahertz (THz) radiation at metal-free space interface. We present a novel model for THz radiation generation using two lasers, beating at a metal surface in the presence of a magnetic field. This interaction resonantly excites a SPW, leading to the generation of THz plasmon. Two co-planar lasers having frequency difference of effective electron plasma frequency exert a ponderomotive force to the skin layer of the metal, which induces an oscillatory velocity to the surface electrons and drives the surface plasma waves. The transverse component of the SPW leads to the generation of electromagnetic radiation at THz frequency. Furthermore, the applied external magnetic enhances the transverse current associated with the SPWs. As a result, the THz field strength increased significantly. An expression of THz radiation field is obtained and the field scaling with the magnetic field has been estimated. Our results reported a better THz conversion efficiency for an optimized magnetic field strength. The result of this work delivers a plausible approach to generate THz radiation field from a laser interaction with a metallic surface.