Spot size effects on the stationary envelope of intense laser pulses in plasma

Nonlinear interactions between ultraintense laser pulses and plasmas reveals a great variety of important collective phenomena. Advances in laser technology have made possible compact terawatt lasers capable of generating subfemtosecond pulses at ultrahigh intensities. These ultrahigh intensities result in highly relativistic nonlinear electron dynamics. This paper addresses stationary stage of the interaction of an ultraintense short laser pulse with a plasma including finite spot size effects. The study is based on the approach that accounts for the transversal effects in an average manner. Following the standard method, a reduced wave equation for the slowly varying laser envelope is derived, including nonlinear effects associated with relativistic electron mass variation and relativistic ponderomotive force. Localized and periodic solutions of the envelope equation are presented and compared with the case when the transversal distribution is infinite. It is found that the finite transverse size of laser spot has significant effects on the propagation characteristics of the stationary profiles.