Excitation of terahertz surface magnetoplasmons by nonlinear mixing of laser and its second harmonic on a rippled surface of n type semiconductor

Abstract

We investigated the excitation of terahertz (THz) surface magneto plasmons (SMPs) by nonlinear mixing of laser and its frequency shifted second harmonic on a rippled surface of n-type semiconductor-free space interface. Obliquely incident p-polarized lasers exert a nonlinear ponderomotive force on free electrons of n-type semiconductor. Nonlinear ponderomotive force induce the oscillatory velocities at frequencies 2ω1 and (ω1 − ω2). These oscillatory velocities beat the modulated electron density nq to get the charge density perturbation at (2ω1, 2k1z + q) and (ω1 − ω2, k1z − k2z + q). Perturbed charge density couples with the linear oscillatory velocities to produce a nonlinear current density, which resonantly derives THz SMPs at frequency ω = 2ω1 − ω2 and propagation constant kz = 2k1z − k2z + q. Here, q provides the extra wave number for the phase matching condition. The efficiency of THz SMPs wave attained up to 9% and amplitude of THz SMPs controlled by the electron cyclotron frequency ωce and incident angle θ.

Resonant excitation of terahertz surface magnetoplasmons by optical rectification over a rippled surface of n-type indium antimonide

“…Assume that represents the interface between a rippled semiconductor (n-type) () and free space () with the electron density perturbation (Srivastav & Panwar 2023), where , and are the amplitude and ripple wavenumber, respectively. Apply the magnetic field to the semiconductor (n-type) (cf.…”

“…The effective mass of free electrons inside a semiconductor (n-type) is . The effective permittivities of the semiconductor (n-type) components are presented by , , , is the electron cyclotron frequency, e is electron charge, is the electron plasma frequency, is the collision frequency of electrons and the temperature-dependent electron density of n-InSb (Srivastav & Panwar 2023), where and are the Boltzmann constant and temperature, respectively.…”

“…The electron density in metals is of the order of ≈10 28 m −3 and the corresponding plasma frequency is 10 15 Hz, which lies in the visible region (Deepika et al 2015;Sharma, Ghotra & Kant 2018). In a semiconductor (n-type), the electron density is ≈10 23 m −3 and the relative plasma frequency is of the order of 10 12 Hz, which lies in THz region (Kumar, Kumar & Tripathi 2016a;Gupta 2021;Srivastav & Panwar 2023). The plasma frequency and dispersion relation of SPWs can be tuned with temperature and an external magnetic field, respectively.…”

“…The plasma frequency and dispersion relation of SPWs can be tuned with temperature and an external magnetic field, respectively. Srivastav & Panwar (2023) explored the effect of a magnetic field over the excitation of a THz surface magnetoplasmon (SMP) wave on n-type indium antimonide (n-InSb) by beating the laser and its second harmonic frequencies.…”

“…2015; Sharma, Ghotra & Kant 2018). In a semiconductor (n-type), the electron density is and the relative plasma frequency is of the order of Hz, which lies in THz region (Kumar, Kumar & Tripathi 2016 a ; Gupta 2021; Srivastav & Panwar 2023). The plasma frequency and dispersion relation of SPWs can be tuned with temperature and an external magnetic field, respectively.…”