Three propagation regimes of Laguerre–Gaussian laser beams in collisionless plasma

Nonlinear optical effects in plasmas associated with light beams carrying orbital angular momentum are realizable in the form of Laguerre–Gaussian beams (LGBs) popularly known as twisted light. In this paper, the effect of angular mode index of light on propagation of LGBs in plasma is investigated by considering ponderomotive nonlinearity. A paraxial-like approach is adopted to establish nonlinear differential equation for beam-width parameter. Three distinct regimes characterizing nature of propagation are obtained for different modes of LGBs. The essential critical as well as divider curves and corresponding changes in beam width parameter with propagation distance of LGBs are assessed. It is found that orbital angular momentum of a light beam significantly affects the self focusing characteristics of LGBs in plasma.