OPTICAL BISTABILITY BY NONLINEAR REFLECTION IN A POLYMERIC BLEND

We have analysed the propagation of two continuous-wave Ar+-laser beam s travelling in opposite directions in a two-component nonlinear heter ogeneous medium (the polymeric blend PMMA-EVA), in a mirror retrorefle ction geometry. Bistable ref-lection associated with the laser-induced suppression of scattering is observed. This phenomenon has a thermal origin. Based on light- and heat-transport theory inside the material, a simplified explanation of the experimental evidence is presented, s howing the conditions for the onset of optical bistability. Qualitativ e agreement with our experimental results is found.