Apeiron, Vol. 13, No. 3, July 2006 375 © 2006 C. Roy Keys Inc. — http://redshift.vif.com Light Beam Propagation in a Photorefractive Environment: Beam-Fanning Effect and Amplification of Weak Beams A. Zúñiga-Segundo, M. A. Arvizu-Coyotzi, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Edif. 9, Col. Lindavista 07738 México DF, e-mail: azuniga@polaris.esfm.ipn.mx J.L. López-Bonilla, B.E. Carvajal-Gámez, SEPI-ESIME-Zacatenco. Instituto Politécnico Nacional. Edif. Z-4, 3er. Piso, Col. Lindavista, CP 07738 México DF. E-mail: jlopezb@ipn.mx We investigate the propagation of light in photorefractive media by direct numerical simulation. The two dimensional model is based on solution of nonlinear material equations in steady-state and the equations governing propagation of the optical fields. We present results on fanning effect of a single beam and two-wave amplification in an applied alternating field. Keywords: BSO, photorefractive, space-charge field, electro- optic, fanning effect.