Spatial optical solitons in gyrotropic crystals of sillenites under an dc field

An analysis of existence conditions of the (1+1) spatial optical solitons in the cubic gyrotropic photorefractive crystals under an DC field has performed. The analytical solution for the solitonic envelope, refractive index and polarization state has founded. Formation conditions of the spatial optical soliton in the -plane of crystal of Bi12SiO20 with wavelength of light nm have determined and form dependence of its envelope from external field value has studied.