Optical breathers in nonlinear anisotropic and dispersive media

Anisotropic crystals containing impurity atoms, when the principal optical axis of the uniaxial crystal and the vector of electrical dipole moment of the impurity atoms are perpendicular to each other and are directed along different crystallographic axes, are shown to have three different mechanisms of the formation of breathers depending on the direction of the wave propagation and on the symmetry of the medium. Explicit analytic expressions for the parameters of breathers and the effective nonlinear susceptibilities for extraordinary waves are obtained. All uniaxial crystals with quadratic susceptibilities can be divided into three different groups, according to the crystal classes. Each group is characterized by a universal structure of the breather zones. The structure of the breather zones of the trigonal, tetragonal, and hexagonal crystals with cubic susceptibilities depends neither on the crystallographic system nor on the crystal classes and coincides with the structure of the breather zones of the trigonal and hexagonal crystals with quadratic susceptibilities and crystal classes 3, 3m, (6) over bar, (6) over bar m2. It is shown that structure of breather zones of the different groups of crystals for the cases when the principal optical axis of the uniaxial crystal and the vector of electrical dipole moment of the impurity atoms are mutual parallel or perpendicular to each other are significantly different.