Second harmonic generation by self focused q-Gaussian laser beam in preformed collisional parabolic plasma channel

This paper presents an investigation of self-focusing of a q-Gaussian laser beam and its effect on second generation in a preformed collisional parabolic plasma channel. In the presence of a q-Gaussian laser beam redistribution of carriers takes place on account of nonuniform heating produced due to collisional nonlinearity, as a result of which, a transverse density gradient is established in the channel which in turn generates plasma wave at pump frequency. Generated plasma wave interacts with the incident laser beam and generate second harmonics of the incident laser beam. Moment theory has been used to derive differential equation governing the evolution of spot size of laser beam propagating through the channel. The differential equation so obtained has been solved numerically. The effect of the intensity of laser beam, deviation of intensity distribution of laser beam along its wavefront from Gaussian distribution, plasma density and depth of channel on beam width of laser beam as well as second harmonic yield has been investigated.