SPATIAL SOLITONS IN PHOTOREFRACTIVE BI12TIO20 WITH DRIFT MECHANISM OFNONLINEARITY

The analysis performed shows that in cubic photorefractive crystals (o f Bi12SiO20 and GaAs type in particular) with drift (''quasilocal'') m echanism of optical nonlinearity spatial soliton propagation can be ob served for reasonable external de electric fields 10-15 kV/cm. These p hotorefractive solitons which can be excited at very low cw laser powe r are stable in a broad region of signal(soliton)/incoherent(spatially uniform) intensity ratio, and allow easy switching from bright to dar k type. Original experimental results of self-channeling of submicrowa tt HeNe laser beam in a cubic Bi12TiO20 Sample under external de field are presented.