Electric field-induced strong THz emission by beating two filamented spatial-Gaussian lasers in the pre-existing underdense magnetized plasma

Abstract

A novel scheme for electric field-induced strong terahertz (THz) emission by beating two filamented spatial-Gaussian laser beams (with intensities ${10}^{14} {\mathrm{W cm}}^{-2})$ in the pre-existing underdense magnetized plasma is proposed. The coupling between the nonlinear density and nonlinear velocity of the plasma electrons results in the strong nonlinear current which drives the efficient THz radiation in the presence of the D.C. electric and magnetic fields. The contribution of the electron temperature on the THz generation has been investigated. The modulation index also makes a significant contribution to the enhancement of the nonlinear current density and normalized THz amplitude. With the help of a magnetic field, D. C. electric field, D.C. drift speed, and modulation index, one can easily tune the THz radiations for medical and astronomical applications. The normalized amplitude of emitted THz radiation is observed to vary with the externally applied electric field, magnetic field, normalized frequency, drift velocity of electrons, thermal velocity of electrons, temperature of plasma electrons, and modulation index of incident laser beams. The frequency of the emitted THz radiation (corresponding to $25.0\mathrm{ kG}$) is found to lie in the frequency range of molecular rotational and vibrational spectra of deoxyribonucleic acid. As a result, emitted THz radiation in the present scheme can play an important role in developing a new technique to distinguish between healthier and non-healthier tissues of human beings. The emitted THz radiation shows sensitive behavior toward water particles. Due to this, emitted THz radiation can also be used to detect water at the surface of the earth as well as on other celestial bodies.