arXiv subjects

Rohit Kumar Srivastav

Publications and source records attributed to Rohit Kumar Srivastav.

3 recordsLinked to original sources

arXiv2026

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

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.

physics.plasm-ph↗

arXiv2025

Enhanced Terahertz Generation via Oblique Incidence of Unipolar Laser Pulses on Plasma

We investigate terahertz (THz) radiation generation at the vacuum-plasma interface driven by the oblique incidence of s-polarized Gaussian laser pulse(s) on a semi-infinite underdense plasma.~Extending beyond the conventional single-frequency bipolar pulse (B-pulse), this work focuses on leveraging two-color mixed-frequency pulse-- (M-pulse) excitation to enhance THz performance in terms of strength and broadening that can be tuned through controlled amplitude and phase of the constituent pulses of the M-pulse. A new expression for the ponderomotive force (PF) -- which acts as the main driver of THz radiation at the vacuum-plasma boundary -- is derived to capture the hitherto unexplored effects of phase asymmetry intrinsic to the M-pulse, in contrast to a single B-pulse where its phase is irrelevant. This PF formulation captures the underlying cycle-to-cycle symmetry-breaking for the M-pulse field, responsible for efficient THz emission. We demonstrate analytically that such M-pulses of the same total energy as a B-pulse may generate significantly enhanced PF, leading to THz yields several orders of magnitude higher. With a judicious choice of low-frequency to high-frequency ratio, the M-pulse configuration is shown to emerge as a highly efficient, phase-controllable driver of THz radiation and offers a promising route for optimizing THz source design via tailored two-color laser-plasma interactions.

physics.plasm-ph↗

arXiv2025

Terahertz radiation generation by laser-resonant excitation of terahertz surface magnetoplasmons on a graphene-n-InSb semiconductor interface

We propose a method for the laser-excitation of terahertz surface magnetoplasmons via the linear mode conversion of terahertz radiation on a graphene sheet deposited on an n-type semiconductor in presence of an external magnetic field parallel to the semiconductor surface. An obliquely incident p-polarized laser beam interacting with the graphene n-InSb semiconductor surface, imparts linear oscillatory velocity to the free electrons. This oscillatory velocity couples with the modulated electron density to generate a linear current density, which resonantly excites terahertz surface magnetoplasmons. It is shown that the amplitude of terahertz surface magnetoplasmons wave can be tuned by adjusting the external magnetic field ($\text{B}_{0}$), the graphene's Fermi energy ($\text{E}_\text{F}$), the semiconductor's temperature (T), and the incident angle ($θ$) of laser. This mechanism has the potential to enable the development of an actively tunable plasmonic device.

cond-mat.mes-hall↗