Nonlinear processes in the optical medium of a high power neodymium laser

Mechanisms for the occurrence of nonlinear processes during the propagation of high power beams in the optical medium of a short-pulse neodymium laser are discussed. Particular consideration is given to the occurrence of self-focusing (both temporal and spatial) in oscillators and amplifiers of high power neodymium lasers. Methods for the suppression of self-focusing in such devices are presented, including amplification in divergent beams, supression of harmful diffraction effects, the use of spatial filters, and the fragmentation of the active medium.