The article is а review of publications on parametrically bound three-wave solitons in dispersive anisotropic media with quadratic nonlinearities. The character of cooperative self-action of plane monochromatic waves is studied. The properties of space and time solitons are discussed in the framework of quasi-optical diffraction theory and of the second approximation of linear dispersion theory with regard to the detuning of phase and group velocities. А simple model is considered of mutual focusing of beams and pulses in а medium with quadratic nonlinearity. BistaЫe solitons are analyzed for the case of interference between two channels of wave packet reactive interaction with an integer frequency ratio and in the presence of cuЬic nonlinearity. The evolution of extremely short pulses described in numerical experiments bу nonlinear Maxwell equations is traced. Experimental results of observation of optical solitons in crystals with quadratic nonlinearities are reported.
Department of Radiophysics