二波耦合时光折变晶体取向及入射光振动方向的最佳选择

The Optimum Selections of the Crystal's Orientation and the Directions of Vibration of Incident Beams in the Photorefractive Two-beam Coupling Experiment

首先提出全面寻找最佳取向的理论方法,并具体运用此一理论找出了几个最佳取向及较好取向的实例。

A general theoretical method for the selection of the optimum orientation in the photorefractive two-beam coupling experiment is introduced. The magnitude of energy (AIa) transfered from beam b to beam a in a photorefractive two-beam coupling experiment has been expressed as a function of θ, φ, (?) (parameters to specify the orientation of crystal) and α, β (parameters to specify the direction of vibration of the incident beams). By this function, the optimal values of these parameters are calcu-leted to find out the greatest and maximum values of (△Ia). For the illustrations of this method, some practical examples (For GaAs, KNbO3, BaTiO3…crystals) are given. The results from these examples indicate that the coupling effect may be stronger than usual by 30% for BaTiO3 and KNbO3 when orientated properly. And the effect is stronger for GaAs when the direction of polarization of incident beams are parallel to one direction of eigen polarization, rather than perpendicular or parallel to the incident plane (when these two directions are different).