Terahertz field generation from laser interaction with spherical nano-particles: effect of external magnetic field

Present study investigates the THz field generation from laser beat wave interaction with spherical nanoparticles (NP_s) in presence of external magnetic field. A cluster of electrons and ions creates during laser interaction with spherical NPs and surface plasmon oscillations generate at surface of spherical cluster with characteristic frequency of \({\omega }_{p}/\sqrt{3}\). Oscillatory current produces at beat-wave frequency \((\omega = \omega_{1} - \omega_{2} )\) under the influence of laser imparted ponderomotive force. Oscillatory nonlinear current \({(J}_{NL})\) induces electromagnetic field \({(E}_{THz}/{A}_{0})\) in THz frequency range. Field decentred (FDC) parameter \(\left(\delta \right)\) is introduced in laser field profile that redistributes the laser energy in space; external magnetic field is applied in transverse direction. THz field amplitude is estimated with respect to terahertz frequency under the variation of FDC parameter \(\left(\delta \right)\), Magnetic field strength (B) and amplitude of the density perturbation \({(n}_{q}/{n}_{0})\). THz amplitude enhances significantly in presence of magnetic field with multiple resonance. Also, damping mechanism in plasmon oscillations of NPs can be controlled using laser intensity redistribution in polarization direction.