Propagation of circularly polarized quadruple Gaussian laser beam in magnetoplasma.

The propagation of circularly polarized quadruple Gaussian laser beam in underdense magnetoplasma has been investigated. The effect of externally applied axial magnetic field on self-focusing of a laser beam is seen in the presence of relativistic nonlinearity. The nonlinearity arises due to the relativistic increase in mass of electrons which modifies the plasma frequency and hence the refractive index profile. Self-focusing of quadruple Gaussian laser beam in the presence of an externally applied magnetic field is found substantially improved in the case of extraordinary mode and reverse is true for the ordinary mode. Our results reveal that the propagation of the quadruple laser beam can be studied in three different regimes i.e. steady divergence, oscillatory divergence, and self-focusing regime depending on the initial point. For initial point not lying on the critical curve, the beam width parameter will either increase or decrease. The beam is more focussed at lower intensity in both cases viz. extraordinary and ordinary mode. [ABSTRACT FROM AUTHOR]