  The models of the non-linear optics in which solitons were appeared are
considered. These models are of paramount importance in studies of non-linear
wave phenomena. The classical examples of phenomena of this kind are the
self-focusing, self-induced transparency, and parametric interaction of three
waves. At the present time there are a number of the theories based on
completely integrable systems of equations, which are both generations of the
original known models and new ones. The modified Korteweg-de Vries equation,
the non- linear Schrodinger equation, the derivative non-linear Schrodinger
equation, Sine-Gordon equation, the reduced Maxwell-Bloch equation, Hirota
equation, the principal chiral field equations, and the equations of massive
Thirring model are gradually putting together a list of soliton equations,
which are usually to be found in non-linear optics theory.
