Abstract
The photorefractive effect in barium titanate (BaTiO3) under high-intensity illumination is modeled. The analysis considers both photocarrier saturation due to strong photoionization and a consequent intensity-dependent change in the relative contributions of hole and electron conductivity. An expression for the exact solution of the space-charge field under high-intensity illumination is presented for photorefractive media with both hole and electron conductivity. In the case of BaTiO3, the intensity dependence of the hole–electron competition arises from an effective increase in hole trapping sites (and electron photoionizing centers), which is due to a large photoionized carrier population. The model explains experimental results in which a crystal that is hole dominated at low intensity is converted into electron-dominated photoconductivity at high intensities when using nanosecond pulse illumination.
© 1993 Optical Society of America
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