High-performance liquid crystals for next-generation in formation technologies

全息图，一个三维度图像的光学存储，对光子应用有很大的兴趣。为了获得清晰的图像，布拉格全息图，理论上实现1 O 0- %的差异效率是必需的。在布拉格全息图中，材料应该是光学上敏感的，这意味着反射性指数被光线有效地改变了。液体晶体，显示出较大的光学异构体和流体性，可以是全息材料的好候选人，因为折射指数中的较大变化可以很容易地被外部领域所诱导。全息图中还有另一个重要的特征：记录的可逆性。商业上可用的材料足够敏感，如果图像不能被擦除，那么光器件的应用将受到限制。偶氮烯是一种具有改变吸收、分子形状和反射性指数的优秀的光致色分子，它是一种能够在光辐射上改变的光致色分子。Consequently， Polymer Liquid Crystals Incorpora ... More 泰德与氮氧化物活力自然被认为是可逆的全息材料。在本研究中，有两种全息图类型、转移类型和Lippmann类型，使用聚合物氮氧化物液体晶体薄膜进行了调查。一个来自Ar^+激光器的线性极化光束在488纳米处分裂成两束光束，并在薄膜中与传输类型的14度交叉，180度在Lipmann-type中交叉，对此，表示赞赏。传输类型Grating的形成行为是一个探测器，带有一个线性极化光束从He-Ne激光器在633纳米。Lippmann型赠款被评估为传输谱。在传输类型中，探测光束的差异在488纳米处出现在写入光束上的辐射。Diffraction efficiency （η），定义为在辐射之前传输强度的比率，在辐射之前增加到14%的光辐射。在另一边，在Lippman类型的研磨中，500纳米光的Q值达到43%时，电影的辐照度为350毫瓦/厘米^2，低于60分钟。

Holography, which enables optical storage of three-dimension images, has been of great interest for photonic applications. To obtain clear images, Bragg hologram that theoretically achieves 1O0-% diffraction efficiency is required. In the Bragg hologram, materials should be optically sensitive, meaning that refractive index is efficiently changed by light. Liquid crystals, showing large optical anisotropy and fluidity, can be a good candidate for holographic materials since a large change in refractive index can be easily induced by external fields. There is another important characteristic in the hologram : reversibility of recording. Commercially available materials are sensitive enough, while images cannot be erased, which limits the application to photonic devices. Azobenzene is one of the outstanding photochromic molecules that are capable of changing absorption, molecular shape, and refractive index reversibly upon photoirradiation. Consequently, polymer liquid crystals incorpora … More ted with an azobenzene moiety are naturally expected to be reversible holographic materials.In this study, two types of hologram, transmission-type and the Lippmann-type, were investigated using polymer azobenzene liquid crystal films. A linearly polarized beam from Ar^+ laser at 488 nm was split to two beams and interfered in the film with a crossing angle of 14゜ in transmission type and 180゜ in the Lippmann-type, respectively. Formation behavior of the transmission-type grating was probcd with a linearly polarized beam from He-Ne laser at 633 nm. The Lippmann-type grating was evaluated with transmission spectrum. In the transmission type, diffraction of the probe beam appeared upon irradiation of writing beams at 488 nm. Diffraction efficiency (η), that is defined as the ratio of diffraction intensity during irradiation to transmission intensity before irradiation, increased to 14% on photoirradiation. On the other hand, in the Lippman-type grating, the value of q for 500-nm light reached 43% when the film was irradiated at 350 mW/cm^2 for 60 min. Less