Supplementary optical phase transition in photorefractive coherent oscillator

The semilinear photorefractive coherent oscillator with two counterpropagat ing pump waves may exhibit two optical phase transitions: one from a disord ered state of wide-angle photorefractive scattering into a high-ordered sta te with the immobile photorefractive grating and the other one from the sta te with immobile grating into the state with two moving photorefractive gra tings. We show, both experimentally and from calculations, that two these p hase transitions are the second-order phase transitions. (C) 2001 Elsevier Science B.V. All rights reserved.