Superluminal light pulse propagation via rephasing in a transparent anomalously dispersive medium

We study the propagation of light pulses through a transparent anomalous dispersion medium where the group velocity of the pulse exceeds c and can even become negative. Because the medium is transparent, we can apply the Kelvin's method of stationary phase to obtain the general properties of the pulse propagation process for interesting conditions when the group velocity: U < c, U = ±∞, and even becomes negative: U < 0. A numerical simulation illustrating pulse propagation at a negative group velocity is also presented. We show how rephasing can produce these unusual pulse propagation phenomena.