【摘要】 研究了弱线偏振光(≈0.16W/cm2)通过垂直排列C60掺杂的向列相液晶(5CB)薄膜的远场衍射图样.基于取向光折变机理,二波耦合使液晶分子进行二次取向之后,强度为高斯分布的光束通过样品时将形成高斯分布的空间电荷场,偏振光束通过样品时将产生偏振衍射图样.衍射图样的轮廓是同心圆环,在垂直于光的偏振方向有对称缺口.改变入射光的偏振方向可以看到衍射图样也随之改变,有效非线性折射率系数n2≈0.3cm2/W.从理论上对实验现象进行了解释.更多还原

【Abstract】 Anisotropic diffraction patterns were observed on far-field screen induced by a weak（≈0.16 W/cm2） linearly polarized collimated beam passing through a homeotropic C 60 -doped nematic liquid crystal（5CB） cell.Based on orientational photorefractive effect,two-wave coupling experiment was carried out to induce liquid crystal molecule re-orientation.The form of space-charge field with the Gaussian distribution induced by the Gaussian beam incident on the sample is investigated.The outline of far-field diffraction pattern is concentric ring,and shows symmetrical gaps in the direction perpendicular to the direction of polarization of light.In addition,diffraction pattern changes when the polarization of the incident light is changed,effective nonlinear index coefficient is n₂≈0.3 cm2/W.The results showed that our theoretical analyzsis was consistent with the observed experimental phenomena.更多还原