Exploring propagation regimes of amplitude-modulated dark and antidark Gaussian laser beams in plasma

In this work, we analyzed three distinct propagation regimes of amplitude-modulated dark and antidark Gaussian (DADG) laser beams in plasma by considering ponderomotive nonlinearity. Based on Wentzel-Krammers-Brillouin (WKB) and paraxial approximations, the nonlinear differential equation for the beam-width parameter of DADG beams is derived. The behaviour of DADG beams propagation is elucidated through the analysis of critical and divider curves. The dependence of the beam-width parameter on propagation distance is illustrated for different values of the modulation parameter of DADG beams. The relevance of axial intensity and dielectric function with the dependence of the beam-width parameter of DADG beams on the distance of propagation has been illustrated. Further, the effect of plasma temperature and inhomogeneity on the self-focusing of DADG beams in plasma has been explored. The fundamental Gaussian beam is obtained as a particular case of the present study. Our results show that the self-focusing of antidark (dark) Gaussian beams is more (less) pronounced as compared with fundamental Gaussian beam.