Effects of disorder and doped trap concentration on the formation of space charge field (SCF) associated with photorefractivity of nonlinear optical polymers were studied in points of the dipole interactions by Monte-Carlo simulation. Energetic disorder of the charge carriers is assumed to arise from inhomogeneous interactions between the charge and electric dipoles of neighboring molecules. This study reveals that the intensity of SCF at steady state depends strongly on the magnitude of the electric dipoles of trap molecules in conjunction with their concentration, and that there exists a correlation between the trap dipole and concentration for the optimal formation of SCF. (c) 2006 Elsevier B.V. All rights reserved.