Compensation of nonlinear distortions in the amplification stages of laser systems with wavefront reversal

The output radiation of a high-power multistage amplifier with an active element (AE) of rectangular cross section with wavefront reversal (WFR) is calculated, taking into account the nonlinearity of the optical medium of the AE, the amplification inhomogeneity, and thermooptical distortions. It is shown that under certain conditions the WFR in this type of system does not produce total compensation of the nonlinear distortions of the wavefront, even in the case of ideal reflection from the Brillouin mirror. Instead, a nonlinear compensator is proposed for these distortions, which consists of a system of elements with a passive nonlinear medium.