基板表面锚泊对液晶全漏导模影响的理论研究

平行排列向列相液晶盒基板表面锚泊能可以影响液晶盒内液晶分子指向矢的分布,光学上将导致液晶导模结构的变化。为了研究基板表面锚泊对液晶全漏导模的影响,首先基于液晶弹性理论推导了液晶指向矢在外加电压下满足的平衡态方程,随后由差分迭代方法数值计算液晶指向矢。最后,基于液晶多层光学理论推导了液晶导波反射率和透射率公式,并通过数值计算得到了平行排列向列相液晶全漏波导反射率Rss随内角变化的理论曲线。计算结果表明,相对于强锚泊情形(1×10~(-3) J/m~2),不同锚泊能强度(5×10~(-5) J/m~2～1×10~(-3) J/m~2)下的理论曲线会发生左移现象,移动距离与锚泊能强度有关。由曲线移动的距离可以确定液晶盒基板表面锚泊能的强度。该研究为进一步利用光导波技术测量液晶盒基板表面锚泊能强度提供了理论依据。

Theoretical study of the surface anchoring effect on the full leaky waveguide mode of liquid crystal

Surface anchoring energy of the substrates can affect the distribution of liquid crystal director in parallel-aligned nematic liquid crystal cell, and the structure of liquid crystal guide mode will be changed in the optics. To investigate the influence of the anchoring energy on the liquid crystal fully leaky guided mode, the equilibrium equation of the liquid crystal director was deduced under the external applied voltage based on the elastic theory of liquid crystal, and then the liquid crystal director was numerically calculated by the differential iteration method. Finally, the formula on reflectivity and transmittance of liquid crystal waveguide was obtained based on the multilayer optics theory of liquid crystal. The theoretical curves of R_ss versus internal degree were calculated in this paper. The results show that the theoretical curves of different anchoring energy strength (5×10^-5J/m²~1×10^-3J/m²) will be shifted to the left compared with the strong anchoring (1×10^-3J/m²) condition, and the moving distance is related to the anchoring energy strength. The anchoring energy strength of substrate surface can be determined by the moving distance of the curves. This study provides a theoretical basis for further measuring the anchoring energy of the substrates in a liquid crystal cell by using optical guided wave technique.