Second harmonic generation of zeroth-order Bessel-Gaussian laser beam in collisionless plasma

Abstract

The objective of present work is to investigate second harmonic generation (SHG) of zeroth-order Bessel-Gaussian (B-G) laser beam in collisionless plasma. The ponderomotive force produces density gradients in plasma by expelling the plasma electrons from high field portion to low field portion thereby modifying plasma’s refractive index. This modification causes self-focusing of main beam. The density gradient further causes excitation of electron plasma wave (EPW) at the main beam frequency. The excited EPW couples with input beam thereby generating second harmonics. The well known WKB approximation and moment theory are employed for obtaining non-linear differential equation for laser beam’s spot size and expression for SHG yield. Further, numerical solutions of these equations are obtained by well known RK-4 method. It has been concluded from the present analysis that transverse component of wave parameter μ, normalized laser intensity and plasma density plays a significant role in affecting laser beam self-focusing and its SHG yield. Results from the present study are important for the laser induced plasma.