Effect of self-focusing on third harmonic generation by a Gaussian beam in a collisional plasma

Abstract

In this paper the third harmonic generation caused by the self-focusing of a Gaussian electromagnetic beam in collisional plasmas has been investigated. The wave equations for the fundamental and the third harmonic fields have been solved in the paraxial approximation. The wave frequency has been assumed to be much larger than the electron collision frequency. The generation of the third harmonic considering self-focusing has been investigated and graphically presented. It is seen that the self-focusing of the fundamental beam enhances the power of the third harmonic output indicating that the region of third harmonic generation is localized near the axis of the beam. The dependence of the third harmonic power on the distance of propagation for different values of initial fundamental power, beam width, and plasma density has also been plotted and discussed.