光的偏振态对向列相液晶中光栅衍射的影响

通过二波耦合实验研究了不同偏振态的两束写入光在向列相液晶中形成光栅的衍射现象。实验发现,水平偏振态(P-P偏振)照射时形成的光栅具有比竖直偏振态(S-S偏振)照射时大得多的能量耦合,且能量耦合方向完全相反。更重要的是,当光栅形成之后改变其中一束光的偏振方向时,透射光和衍射光的强度会随着其中一束光的偏振态的改变而变化。可见,光的偏振态在决定NLC分子非线性取向时是一个非常重要的参数,在以后的光电子功能器件应用中与偏振光相关的分子取向产生的非线性光学现象将会非常有用。

Influence of Light Polarization on Two-beam Coupling in Nematic Liquid Crystals

An experimental investigation on diffraction of two different polarized incident lights in C60-doped Nematic Liquid Crystal (NLC) homeotropically aligned is reported. The experiment shows that much greater energy transfer is created in grating recorded by horizontal polarization (P-P polarization) beams than that by vertical polarization (S-S polarization) ones, and the energy transfer direction is totally opposite. It is shown that when one incident beam polarization state is changed, the intensity of diffraction and transmitted beam will be changed accordingly after the grating is written. The polarization state is a very important parameter in the determination of nonlinear reorientation NLC. Nonlinear phenomena caused by molecular reorientation and their dependence on light polarization should be very useful in potential applications for optoelectronic functional elements.