Superluminal light propagation in a normal dispersive medium

The propagation of a Laguerre-Gaussian (LG) beam through dispersive medium is investigated. effect the doughnut-like intensity profile probe LG on group velocity studied. We find an analytical expression for out optical axis and compare with its projection onto axis. It turned that vector along at waist Rayleigh range. numerically analytically investigate helical phase front coupling field in four-level double V -type quantum system. Our analysis predicts strange behavior inside normal gain region so it can exceed speed light free space, leads to gain-assisted superluminal dispersion. Such unusual results from distortion via classical interference planar fields. obtained may some potential applications increasing information transmission communications.