Influence of Rippled Electron Density and Refractive Index on Second Harmonic Generation of Super-Gaussian Pulses in Inhomogeneous Plasmas

Abstract

Effects of rippled electron density, the intensity of the laser beam, and the refractive index on the second harmonic generation of super-Gaussian pulses in inhomogeneous plasmas are investigated. Using the magnetic field of the laser beam and the quiver velocity of the electrons, the second harmonic nonlinear ponderomotive force is obtained. This nonlinear force pushes electrons which generates a space-charge force and nonlinear electron velocity. This leads to the nonlinear current density. Using the linear and nonlinear current densities and Maxwell's equations, the equation of the second harmonic electric field is obtained. Results show that by increasing the laser intensity and the amplitude of the ripped electron density, the absolute value of the second harmonic electric field amplitude increases. By increasing the refractive index of the plasma, the amplitude of the second harmonic wave decreases.