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 (NPs) 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 ω p / 3 . Oscillatory current produces at beat-wave frequency (ω = ω 1 - ω 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 δ 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 δ , 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. [ABSTRACT FROM AUTHOR]