Spatial hysteresis and switching waves in a nonlinear planar waveguide

An experimental investigation was made of the transformation of the intensity profile of a spatially confined light beam reflected from a nonlinear planar waveguide. It was found that when the system exhibited optical bistability, a hysteresis of the intensity profile was observed and it was due to the formation and propagation of a switching wave in the waveguide layer. A hysteresis was also observed when a switching wave crossed the unilluminated part of the waveguide layer.