Short laser pulse parameters in a nonlinear medium: different approximations of the ray-pulse matrix

The purpose of this paper is to find an expression to describe the evolutio n of the temporal parameters of a short laser pulse crossing a Ken nonlinea r medium, suitable to be recast in a form consistent with the standard form ulas for Gaussian beam transformations, via 2 X 2 ray pulse matrices. The g oal is to find a satisfactory compromise between accuracy and simplicity. E xpressions with different degree of approximation are analyzed and their va lidity and accuracy are discussed. (C) 2000 Elsevier Science B.V. All right s reserved.