Light-induced charge transport processes in photorefractive crystals I: Models and experimental methods

Abstract

Light-induced charge transport processes are essential for photorefractive effects in eleclrooptic crystals. Charge driving forces, charge transport models and experimental methods for investigation of charge transport processes are reviewed. - Drift, hulk photovoltaic currents and diffusion are the charge driving forces. The one-center model without and with electron-hole competition and two-level models, i.e., the two-center model and the three-valence model, are described. The special features of the different models in the case of homogeneous and inhomogeneous illumination are pointed out. Methods for reliable measurements of absorption, light-induced absorption changes, dark and photoconductivities, amplitude and phase of refractive index and absorption gratings, and of charge carrier mobilities are presented.