This paper presents an analysis of the relativistic self-focusing of a
rippled Gaussian laser beam in a plasma. Considering the nonlinearity as arising
owing to relativistic variation of mass, and following the WKB and paraxial-ray approximations, the phenomenon of self-focusing of rippled laser beams is
studied for arbitrary magnitude of nonlinearity. Pandey et al.
[Phys. Fluids82,
1221 (1990)] have shown that a small ripple on the axis of the main beam grows
very rapidly with distance of propagation as compared with the self-focusing of
the main beam. Based on this analogy, we have analysed relativistic self-focusing of rippled beams in plasmas. The relativistic intensities with saturation
effects of nonlinearity allow the nonlinear refractive index in the paraxial
regime to have a slower radial dependence, and thus the ripple extracts
relatively less energy from its neighbourhood.
Optical guiding of intense Hermite–Gaussian laser beam in preformed plasma channel and second harmonic generation