Optical guiding and stability of intense short laser pulses in plasma channels

Laser pulse propagation can be strongly influenced by nonlinear effects (relativistic and/or atomic electrons), ionization processes and finite pulse length effects. In this paper these processes are included in the analysis of the propagation and stability of intense laser pulses in plasmas. An envelope equation, which includes ionization and nonlinear effects, is derived and the spot size is found to be unstable to an ionization-modulation instability. Short laser pulses propagating in plasma channels are found to undergo an envelope modulation that is always damped in the front and initially grows in the back of the pulse. An example of laser wakefield acceleration to electron energies greater than 2, 5 GeV in a plasma channel is described.