Dispersion of a femtosecond wave packet focused by an axicon. a scaling parameter

We investigate the propagation of a femtosecond wave packet focused by an axicon in the linear medium. We introduce a scaling parameter for the problem of the Bessel–Gaussian beam formation in the femtosecond light. This parameter is based on a multiplicative representation for spatiotemporal distribution of the light-field complex amplitude. In this approach, the systematic error for estimating the wave-packet energetic parameters is determined. The approximate method presented can be used for analyzing a femtosecond laser-pulse filamentation under axicon focusing.