Self-focusing of Gaussian Laser Beam Through Collisionless Plasmas and Its Effect on Second Harmonic Generation

This paper presents an investigation of self-focusing of gaussian laser beam in a collisionless plasma and its effect on second harmonic generation. In the presence of gaussian beam, the carriers get redistributed from the high field region to low field region by ponderomotive force and transverse density gradient is established in plasma which in turn generates the plasma wave at pump frequency. This plasma wave interacts with incident laser beam and a second harmonic is generated. Furthermore, if the initial power of input beam is more than the critical power for self-focusing, the beam gets self-focused and hence the generated plasma wave and second harmonic which depend upon the background electron concentration and power of the main beam also get modified accordingly.