Amplification of short light pulses with a spherical wavefront

The propagation of a conical light beam through an optical amplifier is considered. The theoretical analysis is based on an analogue of the system of Frantz-Nodvik equations taking into account the specific character of spherical waves. The conditions of applicability of reduced equations (in slowly-varying amplitude approximation) for describing spherical waves propagating in a nonlinear medium are formulated. The peculiarities of amplification for different values of the beam divergence are compared. The change in the transverse structure of a diverging beam, which appears due to the amplification saturation, is studied. (laser beams)