Resonant excitation of terahertz surface magnetoplasmons by two p-polarized beating lasers interacting on a graphene-n-InSb surface

Abstract

A mechanism of resonant excitation of surface magnetoplasmons (SMPs) is proposed in the terahertz (THz) frequency range by {\emph{beating of two p-polarized lasers}}, obliquely incident at an angle $θ$ on a graphene sheet deposited over a rippled surface of a magnetized n-type semiconductor. The resulting laser-beat-envelope induces a nonlinear velocity to free electrons, which couples with the modulated charge carrier density and generates a nonlinear current. This time-varying oscillating nonlinear current acts as the source of THz SMPs wave generation, as opposed to THz generation by a different process with {\emph{a single laser}} in the earlier work [Phys. Rev. E 113, 015208 (2026)] where light dispersion characteristics as well as the required phase-matching conditions are markedly different. The resulting THz SMPs field amplitude is shown to be controlled in the frequency range of $2-5$~THz by varying the graphene's Fermi energy ($\textrm{E}_\textrm{F}=20-130$ meV), laser incident angle ($θ= 0-90^{o}$), the semiconductor's temperature ($T = 320 - 380$~K) and external magnetic field ($\textrm{B}_{0} \approx 0 - 0.09 $~T). The amplitude of THz SMPs field now reaches on the order of $10^{-1}$ w.r.t. the incident field amplitude, and it is almost $10^1 - 10^2$ fold higher compared to previous works. Thus, the proposed mechanism may open new avenues for the development of actively tunable plasmonic device, with potential applications in future THz technologies and 6G wireless communication systems.