作为光存储材料的有机光致聚合物材料研究进展

本文综述了光致聚合物的光化学反应和动力学基本原理 ,讨论了影响光聚物光存储性能的各个因素 ,对近几年光致聚合物材料的发展状况和光聚物在光全息存储方面所具有的巨大潜力进行了论述     

绿敏光致聚合物的制备及其光全息存储性能研究

报导了一种新型的对绿光敏感的光致聚合物材料。该材料以丙烯酰胺为单体，由光引发剂，共引发剂，成膜物等组成。本材料记录的全息图衍射效率可达55％。在光聚物上采用角度复用技术存储了10幅图像，得到的再现像信噪比较高。说明该材料适合于大容量体全息存储。     

偶氮类有机材料光致双折射的测量

研究了2种偶氮聚合物薄膜的光致双折射效应,并探讨了泵浦光偏振态和光强对光致双折射的影响.采用远离共振区的He-Ne光(633nm)作为探测光,用Ar+激光(488nm)作为泵浦光,通过测量相关参量得到了样品的光致双折射值.实验结果表明:改变泵浦光的偏振态可以控制光致双折射值和探测光的透过信号强度,在0°～45°范围内,泵浦光光强存在最佳值,此时偶氮薄膜实验样品具有最大的双折射值.     

干法在线处理全息存储材料

综述了干法在线处理全息存储材料在高密度数字全息存储中的应用。详细介绍了光折变材料、光致聚合物和光寻址聚合物的基本组成、全息存储性能及其优缺点等。最后,对干法在线处理全息存储材料的发展现状和前景进行了简要介绍。     

不同类型偶氮材料光致双折射的温度特性研究

在不同温度下,分别测量了掺杂偶氮材料、偶氮聚合物和偶氮液晶聚合物的光致双折射行为,并利用双e指数模型对光致双折射的动力学过程进行了拟合.实验结果表明,偶氮材料的光致双折射源于偶氮分子的光致异构和光致分子取向,光致双折射大小随温度的升高表现出先增大后减小的趋势.在抽运光的作用下,含偶氮材料的光致双折射包含一个由偶氮分子取向引起的快过程和一个由偶氮分子带动大分子取向引起的慢过程.关闭抽运光后,掺杂偶氮材料和偶氮聚合物表现为可逆的弛豫,而偶氮液晶聚合物则展现出长久光存储特性.     

新型掺偶氮苯聚合物的取向增强及全息存储

研究一种新型的并列式的高密度存储材料ADPA-PVK-PBA-TNF聚合物薄膜.在非吸收区用光抽运测试法研究了薄膜光致双折射,获得光致双折射变化值Δn=1.3×10^-3,分析了该聚合物薄膜光致取向增强的物理和化学机理.探讨了抽运光对光致双折射的增强和抑制效应.在此基础上初步实现了多重角度复用信息存储、获得了较为清晰的全息存储图像.并讨论了图象存储的增强/抑制效应,利用这种效应可对存储图像处理或删除. 关键词： 掺杂偶氮苯聚合物薄膜 光致双折射 光全息存储 光致取向增强     

一种具有光开关功能的分子材料—光致自旋转换配合物

配合物分子材料的研究是对传统无机和有机材料的一种新发展和挑战．光致自旋转换配合物可望是实现光开关和记录信息的理想体系．     

含氟红敏光致聚合物全息材料的组成优化

用低折射率的含氟共聚物为光致聚合物全息材料的成膜物,以增加全息记录材料折射率的空间可调制程度。用溶液聚合法合成了低折射率的水溶性甲基丙烯酸2,2,3,3-四氟丙酯-甲基丙烯酸共聚物(折射率为1.441),以该共聚物为成膜物质,丙烯酰胺为单体、亚甲基蓝为光敏染料、三乙醇胺为引发剂配制了光致聚合物薄膜;经过对光致聚合物组成构成的优化,在空间分辨力为1580lp/mm时,光致聚合物薄膜的灵敏度约为19 mJ/cm2,衍射效率可达93%,两者均优于以聚乙烯醇(PVA)为成膜物质的光致聚合物材料。     

碱性品红光致聚合物薄膜的光致光衍射

本文研究了全息存储实验中以波长532 nm的半导体激光器作为记录和读出光源,碱性品红作为光敏剂的丙烯酰胺基光致聚合物薄膜的光致光衍射现 象.它可以考虑为透过全息干涉条纹的原始入射光和反射光,与来自光聚物中未曝光的不均匀表面和内部的散射光四波混频的结果.根据简并四波混频理论中的位相匹配条件对双光束全息写入时产生的衍射光锥,以及单光束辐照复现时产生的衍射光锥现象分别做出了理论解释;并且利用全息散射理论结合三角学知识对入射光的入射角与衍射光锥的锥角的依赖关系进行了深入讨论. 关键词： 全息 光致聚合物 衍射光锥 碱性品红     

新型聚偶氮苯取向增强光折变效应及全息存储

合成了新型偶氮分子偶氮二苯胺ADPA(Azo-diphenylamine),将其掺入聚乙烯咔唑Poly(N-Vinylcarba-zole)(PVK)和聚丙烯丁酯(Poly-butylacrylate)(PBA)的聚合物(PVK-PBA)以及三硝基芴酮2,4,7-trinitro-9-flu-orenone(TNF)聚合制成薄膜器件。结果表明掺杂偶氮苯聚合物薄膜在非共振吸收下具有强的光致取向增强光折变效应。光致折射率变化值Δn达到1.3×10-3以上。样品在两相干光束作用下,可建立光折射率光栅,其衍射效率可超过30%,实现了光全息存储。讨论了影响折射率光栅的因素,并对全息存储相关结果形成的机制进行了分析。     

Holographic grating formation in dry photopolymer film with shrinkage

An important issue in developing applications for photopolymers in holography is the effect of shrinkage on recording properties. In this paper, we introduce a model to describe real-time formation of a single grating in photopolymers at any geometrical angle, under the assumption that the shrinkage is in proportion to the polymerization. This model combines polymerization kinetics with the coupled-wave theory, explaining the shrinkage effect on the diffraction efficiency. The model is validated by comparing its predictions with the experimental results for a film of 99μm thickness.     

Ultrafast laser nanostructuring of photopolymers: A decade of advances

Research into the three-dimensional nanostructuring of photopolymers by ultrashort laser pulses has seen immense growth over the last decade. In this paper, we review the basic principles and the most important developments and applications of this technology. We discuss the mechanisms the linear and nonlinear light absorption at tight focusing conditions, and we present some typical laser writing conditions with numerical examples. The photochemistry of traditional and novel photopolymers together with strategies for their photosensitization for laser structuring by ultra-short pulses are discussed. We also discuss current and potential future applications in diverse fields such as metamaterials, plasmonics, micro-optics, and biomedical devices and implants.     

Scattering Noise Properties of Holographic Photopolymers by Means of Real-Time Transmittance Analysis

We propose a simplified model to analyse the temporary behaviour of transmittance for holographic photopolyreefs, based on the existing first-harmonic diffusion theory, with assumptions of constant polymerization coefficient and negligible diffusion effect for noise gratings. By applying this model to measure real-fime transmittance of our novel blue-sensitized photopolymer, the bleaching time constant of dye and polymerization rate are extracted, and the effect of the material composite on the noise property is revealed. This provides a prompt method to assess the performances of holographic photopolymers.     

Toward long lifetime photoinduced spatial distribution of quadratic optical properties in doped photopolymers

A new approach for the spatial photopatterning of the quadratic non-linear optical properties of novel doped photopolymers is presented. The material is composed of a mixture of triacrylic monomers and copolymerizable push-pull chromophores exhibiting quadratic hyperpolarizability. The methods used to perform the photopatterning of the NLO properties and to improve their lifetime is presented along with a model for the thermally induced chromophore orientation relaxation.     

Study on holographic characteristics in ZnMA doped PQ-PMMA photopolymer

The holographic characteristics in phenanthrenequinone and Zinc methylacrylate doped poly-(methyl methacrylate) photopolymers are experimentally studied. The role of ZnMA molecules which is to accelerate the photochemical reaction in material is confirmed by experiment. The doping of ZnMA component results in a higher diffraction efficiency and photosensitivity than typical phenanthrenequinone doped poly-(methyl methacrylate) system. Moreover, the response region and dynamic range are obviously improved.     

Holographic manipulation of nanoparticle distribution morphology in nanoparticle-dispersed photopolymers

We report on experimental verification of mass transfer of nanoparticles during holographic recording in nanoparticle-dispersed photopolymers. Through direct observations of the microscopic structure of recorded holograms as well as optical measurements of the phase shift between the light interference pattern and a recorded hologram we find that holographic exposure causes nanoparticles to be redistributed from bright to dark regions, leading to periodic assembly of nanoparticles and thereby to formation of high-contrast holograms.     

Ultraviolet-Cured Polymer Micro-Optical Elements

A new fabrication method for polymer micro-optical elements is described which uses the contracting effect of photopolymers during the process of polymerization. Convex and concave microlens arrays and phase gratings were formed by irradiating a ultraviolet (UV)-curable monomer with incoherent UV light through an appropriate metallic mask. The morphological and optical characterization of the fabricated elements reveals that the surface profile of the elements depends on the pattern and aperture size of the mask employed.     

Band-edge-induced Bragg diffraction in two-dimensional photonic crystals

Two-dimensional photonic crystals composed of two orthogonal volume diffraction gratings have been photogenerated in photopolymers. When the read beam is set at the Bragg angle, the diffraction efficiency of the transmission grating is strongly enhanced at the band edge of the reflection grating recorded in the material. Such a device provides Bragg operation and enhancement of the diffraction efficiency of the thin diffraction grating together with good wavelength selectivity. Such advantages could be interesting for optical signal processing.     

A review of aspects relating to the improvement of holographic memory technology

Results of studying a holographic memory to write/read digital data pages are presented. The research has been carried out in Novosibirsk, Russia. Great attention was paid to methods of improving recording density and the reliability of data reading, the development of ‘dry’ photopolymers that provide recording of superimposed three-dimensional phase holograms, and the designing of parallel optic input large-scale integration (LSI) for reading and logical processing of data arriving from the holographic memory.