Visualization of Space-Charge Waves in Photorefractive Semiconductor Using Polarimetric Technique

We suggest visualizing space-charge waves (SCW) in the near field in homogeneously illuminated photorefractive crystal, using modulation of optical polarization induced by the SCW due to the Pockels effect. Spatial distribution of SCW is obtained in the near field for a photorefractive semiconductor placed between polarizers. It is shown that the internal field in the crystal is not homogeneous, the SCW at different points are excited with different amplitudes and their structure is not perfectly regular. Qualitative agreement of existing theoretical model with our experimental data is demonstrated. Using the model, the mobility-lifetime product for the free carriers and the effective trap concentration are estimated.