Nonlinear propagation of an optical beam in polymer waveguide with upconverted photobleaching

Summary form only given.Self-controlled optical-beam steering in nonlinear optical media has been intensively studied over the last three decades. We show that refractive-index decrease on upconverted photobleaching leads to an optical beam splitting into multiple beams (optical branching) or to evolution similar to that of a dark spatial soliton in a slab waveguide made of dye-doped polymer. We consider propagation of an optical beam at a wavelength of 633 nm in a slab waveguide made of polymethyl(methacrylate) (PMMA) doped with laser dye 4-dicyanomethylene-2-methyl-6-(P-dimethylamino-styryl)-4H-pyran (DCM).