Nonlinear dynamics of intense laser pulses in a pair plasma

We derive equations for nonlinearly interacting intense laser pulses and an electron-positron plasma, taking into account the combined action of the relativistic particle mass increase and the plasma density profile modification by the relativistic light ponderomotive force. The physical system is described by a modified nonlinear Schroedinger equation (NLSE). The latter predicts a modulational instability and one-dimensional light envelope solitons. In multi-dimensions, we observe the interesting phenomena of light beam focusing, light trapping in self-created density holes, and light beam filamentation. Our results should be useful in understanding the nonlinear propagation of intense laser beams in an electron-positron plasma which could be created by next generation intense lasers