Effects of a single optical beam on photorefractive materials: steady-state solution

Abstract

The band transport model describes charge statics and dynamics within photorefractive materials. Here a steady-state solution is found for the setting in which an arbitrary optical beam illuminates a photorefractive material. The specific case of a Gaussian beam is investigated. The effects of intensity and beam waist are discussed. A comparison is made with previous studies of this problem. It is found that, when the rate of photoexcitation is less than that of thermal excitation, the band transport model can be linearized. In this case the charge density and the space-charge field are proportional to the intensity of the light. On the other hand, when the rate of photoexcitation is greater than that of thermal excitation, the linear solution to the band transport model no longer applies. In this case the charge density and the space-charge field are independent of the intensity and dependent only on the size of the beam waist.