EFFECTS OF OPTICAL-ACTIVITY ON PHOTOREFRACTIVE SPATIAL SOLITONS IN A BIASED BI12TIO20 CRYSTAL

It is shown that the propagation of steady-state spatial solitons in a bismuth titanium oxide (Bi12TiO20) photorefractive crystal is strongl y affected by the presence of concomitant natural optical activity. We assume that the Bi12TiO20 crystal is (110) cut and that the external bias field is along the [00(1) over bar] axis. Such orientation introd uces self-focusing in one polarization of an optical wave front, where as it has no effect whatsoever on the component orthogonal to it. Unde r these conditions, the equations that describe the coupled evolution of the two polarizations of an optical planar beam are derived. Our nu merical study of the interaction dynamics shows that, even though the optical beam experiences periodic diffraction in one of the polarizati on components, it can still recover significantly at particular distan ces within the crystal. Moreover, it is initially capable of maintaini ng its solitonlike form over a certain distance of propagation. Releva nt examples are provided. (C) 1996 Optical Society of America