Photorefractive properties of Cu-doped (K_0.5Na_0.5)_0.2(Sr_0.75Ba _0.25)_0.9Nb₂O₆ crystals with different doping levels and different dimensions

In this article, we studied the photorefractive properties of Cu-doped (K_0.5Na_0.5)_0.2 (Sr_0.75Ba_0.25)_0.9Nb₂O₆ (Cu:KNSBN) crystals with different doping levels. The properties include two-wave mixing and self-pumped phase conjugation, absorption properties, and the growth conditions as well. We also studied the effect of the dimensions on the photorefractive properties. The mechanism of Cu-doped KNSBN and the influence of the different sites occupied by Cu⁺ on photorefractive properties are also discussed. All the experimental results showed that doping levels have much effect on the photorefractive properties. The crystal with a higher doping level has a higher effective charge carrier density, a larger coupling coefficient, and a faster response rate, which is suitable for fast optical information processing. Dimension has much influence on the photorefractive properties. The thinner crystal with the same doping level has a larger coupling gain coefficient, and a shorter response time.