Investigation of induced chirp type and its effect on wake field amplitude in propagation of laser pulse through a plasma channel

In this paper, the propagation of a Gaussian and femtosecond laser pulse through a plasma channel is considered and the amount of induced chirp, as well as it’s type, on laser pulse frequency has been investigated. The group velocity dispersion (GVD) and relativistic effects has been taken into account in propagation equations. It is concluded that the relativistic effect induces positive chirp on laser pulse propagating into plasma channel for every initial chirp, while the GVD effect can induce a negative or positive chirp on laser pulse depending on initial chirp. As the relativistic effect overcomes on GVD in nonlinear region, the induced chirp would be positive. Comparing the results, it is concluded that propagating a laser pulse with initial positive chirp is more effective than a negative and un-chirped pulse for generating a higher wake field.