Self-focusing of Laguerre–Gaussian laser beams in collisionless plasma: paraxial-like approach

The unique characteristic of Laguerre–Gaussian beams (LGBs) is their orbital angular momentum originated from twisting the phase of light into helical shape and forming a spiral. The self-focusing of LGBs in plasma in different physical situations on a certain domains of laser–plasma parameters has a clear physical interpretation, can be easily analysed and could be controlled in an experiment for diverse applications. Present work is therefore devoted to the self-focusing properties of LGBs in collisionless plasma. Considering the ponderomotive nonlinearity, a nonlinear Schrodinger-type equation for the beam width parameter is established analytically with the help of Wentzel–Kramers–Brillouin approximation and paraxial-like approach. The effects of laser parameters and plasma parameters on the self-focusing properties of the LGBs have been explored. The investigation reveals the fact that as vortex charge number of LGBs and plasma electron temperature increases, the extent of self-focusing decreases. Further, with increase in intensity parameter of LGBs and plasma electron density, the self-focusing of LGBs increases.