Phase-type gratings formed by photochemical phase transition of polymer azobenzene liquid crystals : enhancement of diffraction efficiency by spatial modulation of molecular alignment
Phase-type gratings formed by photochemical phase transition of polymer azobenzene liquid crystals : enhancement of diffraction efficiency by spatial modulation of molecular alignment
复制标题
聚合物偶氮苯液晶光化学相变形成的相型光栅：通过分子排列的空间调制提高衍射效率
DOI：
10.1021/jp992172s
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发表时间：
1999
影响因子：
3.3
通讯作者：
T. Ikeda
中科院分区：
文献类型：
--
作者：
Takahiro Yamamoto;M. Hasegawa;A. Kanazawa;T. Shiono;T. Ikeda
在聚合物偶氮苯液晶（PALC）薄膜中形成的相型光栅具有独特的特性。原子力显微镜证实了膜表面的正弦变化。然而，与表面调制的衍射效率的比较表明，该光栅不能仅仅表征为传统的表面浮雕光栅。在薄膜的玻璃态中，在较大的表面调制（68 ~ 76 nm）下获得中等效率（~ 18%），而在向列相(N)中记录的光栅在轻微的表面调制（33 ~ 53 nm）下显示出较高的衍射效率（~ 28%）。在液晶相中，衍射效率得到提高。一阶衍射光束的动力学表明，光栅的形成与PALC的光化学相变有关。假设各向同性(I)相是由干涉图样中偶氮苯部分的光化学反应形成的。
Unique characteristics were observed in phase-type gratings that were formed in a polymer azobenzene liquid-crystal (PALC) film. Generation of sinusoidal variation of the surface of the film was confirmed by atomic force microscopy. However, comparison of the diffraction efficiency with the surface modulation revealed that the gratings could not be characterized only as conventional surface-relief gratings. In the glassy state of the film, moderate efficiency (∼18%) was obtained with large surface modulation (68−76 nm), whereas the gratings recorded in the nematic (N) phase showed high diffraction efficiency (∼28%) with slight surface modulation (33−53 nm). The diffraction efficiency was enhanced in the liquid-crystalline phase. Dynamics of the first-order diffraction beam exhibited that the grating formation was associated with photochemical phase transition of PALC. It was assumed that the isotropic (I) phases were formed by photochemical reaction of azobenzene moieties in the interference pattern at an...