MO—PVA与EO—PVA膜片双色光子存储

首次用ＭＯ－ＰＶＡ、ＥＯ－ＰＶＡ两种样品，在５１４ｎｍ波长光激发下，实现了６３３ｎｍ可擦除光存储，并研究了写入光束对预激发光的依赖关系，用四能级双色光子共振型对各种实验现象进行了解释。     

SA/PMMA的可擦除光存储特性研究

用在聚甲基丙烯酸甲脂（PMMA）中掺杂邻羟基亚甲基苯胺（SA）样品，实现了可见光区域的可擦除光存储。以Ar^ 激光488.0nm线为写入光，He-Ne激光632.8nm线为读出光，研究了光栅生长的动力学过程。在写入和擦除过程中，均观察到了衍射信号随时间先增强后减弱的趋势。探讨了写入光和擦除光功率对衍射信号的影响，依据相干光调制形成相位光栅和光异构产生压力梯度引起分子扩散的光物理过程对光存储机制进行了探讨。     

用于WDM的多重体光栅曝光方法及层状体全息光栅的研究

本文针对层状多重体全息在红外通讯波段分光滤波的应用,分析了其布喇格匹配与衍射效率均匀性问题.给出了在LiNbO3∶Fe光折变晶体中制作层状多重体全息光栅的几种方法.利用双片光干涉在直接分层结构中写入了三层光栅,光栅层厚1 mm,层间距2 mm,每层复用了四个光栅.对这三层光栅的分析测试表明,12个光栅的衍射效率均匀,相邻通道间隔约3 nm.实验结果表明,这种层状结构的多重体全息光栅有希望用来组成具有大量通道数的WDM系统中的复用/解复用器件.     

一种新型偶氮化合物中的高效率实时全息光栅的实验研究

合成了一种新的含偶氮基的三元共聚物，由于在主链中链接柔性基团，使其具有相对较低的玻璃化温度，在６３３ｎｍ处光感生双折射δｎ值可达１０＾－３量级。实验上获得了几个乃至几百微米厚的具有高光学无效性的薄膜，在６３３ｎｍ波长处写一息光栅的实时单光束衍射效率可达１０％以上。     

Eu∶Fe∶LiNbO_3晶体非简并四波混频的研究

用波长为６２３．８ｎｍ的Ｈｅ－Ｎｅ激光作信号光和一束泵浦光，用波长为４８８．０ｎｍ的Ａｒ＋激光作另一束泵浦光，在Ｅｕ∶Ｆｅ∶ＬｉＮｂＯ＿３晶体中实现了非简并四波混频，获得了波长为４８８．０ｎｍ的变频相位共轭光，同时还产生了波长为６３２．８ｎｍ的同频相位共扼光。本文对上述实验结果进行了定性分析。     

高密度体全息存储性能与几何组态的关系

讨论了影响高密度体全息存储性能的动态范围、衍射效率均匀性及布拉格选择灵敏度等三个参量与几何组态之间的关系，强调三者均衡考虑在光路配置中的重要性。利用该均衡原则对LiNbO3晶体进行分析，指出采用O光耦合的90°写入光路为其最佳的几何配置。     

Tc=95K的NdBa2Cu3Ox高温超导外延薄膜的研制

本采用倒筒式直流溅射法原位生长和Ｔｃ值为９５Ｋ的ＮｄＢａ２３Ｃｕ３Ｏｘ外延薄膜，样品的ＸＲＤ分析表明，样品为强烈ｃ轴织构，ｃ轴晶胞参数为１．１７４ｎｍ，样品衍射峰的ＦＷＨＭ＝０．２９°，ＲＢＳ分析表明：薄膜的化学计量为Ｎｄ１．０Ｂａ２．０Ｃｕ３．３Ｏｘ。对影响ＮｄＢａ２Ｃｕ３ＯＸ薄膜Ｔｃ值的因素进行了讨论。     

热释电效应对光折变全息光栅读出的影响

先用两束０.２７ｍＷ的６３２.８ｎｍＨｅ-Ｎｅ激光在掺Ｍｎ的ＫＮＳＢＮ晶体中记录光折变全息光栅，再用波长为６２１.８ｎｍ的准连续染料激光读出，观察到衍射光信号有一个从初始最大值衰减到稳定最小值的暂态过程．初始值对稳定值的比可达７.５以上．这一现象可用热释电效应的影响进行解释 关键词：     

五氧硼酸钾结构的~1H NMR研究

给出相对于外磁场不同取向的五氧硼酸钾（ＫＢ５）单晶的１ＨＮＭＲ室温谱．发现当外磁场在晶体的ｂｃ平面里，１ＨＮＭＲ谱最多有６个峰．而在ａｈ或ａｃ平面里，最多仅有５个峰．用计算机拟合ＮＭＲ谱表明：在五氧硼酸钾中，氢原子是以羟基和水分子集团的形式存在．在羟基集团中，Ｏ—Ｈ的距离为０．１００５±０．００１ｎｍ和０．１０５４±０．００１ｎｍ；而在水分子中，Ｏ—Ｈ的距离为０．０９８３±０．００１ｎｍ和０．０９６８±０．００１ｎｍ，并且Ｈ—Ｏ—Ｈ夹角为１０８°±１°．这些显示本文的数据与中子衍射结果相近，而Ｘ射线衍射所得到的质子位置的数据则与我们的结果相距甚远．     

衍射光学器件光线追迹公式的实验验证

本文介绍了一种衍射光学器件光线追迹的方法，并给出了计算公式。作为验证，在实验室里制作了具有连续相位的体全息器件，将其实际再现光斑与计算点列图进行比较。构造透射体全息片的物光为离轴的球面波，始于轴外点Ａ（０，１３２ｓｉｎ８°，－１３２ｃｏｓ８°），参考光为平面光束，其与Ｚ轴夹角为１７°。激光器采用氩离子激光器（Ｓｐｅｃｔｒａ－ｐｈｙｓｉｃｓＭｏｄｅｌ２０２０），波长４８８ｎｍ；干板感光胶为重铬酸明胶（ＤＣＧ），胶层厚为１５μｍ；通光口径３０ｎｍ。测试时把全息片放在干板的位置。挡住物光，让再现光以和参考光路相同的路径平行入射到全息片上，在全息片后垂直光轴放置毛玻璃片，平行光轴移动毛玻璃片，可观察到－１级衍射光的变化。在距离原点的距离分别为（ａ）４０ｍｍ，（ｂ）７０ｍｍ，（ｃ）８７ｍｍ，（ｄ）９５ｍｍ的地方用ＣＣＤ拍摄了衍射光的形状，与程序计算的点列图在形状和大小上都吻合     

甲基橙偶氮染料掺杂聚乙烯醇薄膜的光存储特性研究

研究了甲基橙(MO)偶氮染料掺杂聚乙烯醇(PVA)薄膜的光致双折射和全息光存储特性.利用YAG激光二倍频(532nm)作为写入光,He-Ne激光(632.8nm)作为读出光,考察了不同染料浓度薄膜的光致双折射,探讨了光致双折射和泵浦光功率的关系,并实现了全息光存储.阐明了MO/PVA光存储的物理机制.     

Polarization-Dependent Light-Gated Phase Conjugation in Methyl-Orange Doped Polymer Film

We have investigated the polarization state of a gated phase conjugate beam using a methyl-orange doped poly-vinyl alcohol (MO/PVA) film in 16 different combinations of linear and circular polarization states of a probe beam and pump beams. The experimental results agree with the theoretical prediction based on the Jones matrix method. Of the third-order nonlinear susceptibility tensors X_ijkl of the MO/PVA film, the X₁₂₂₁ at the 647 nm wavelength in degenerate four-wave mixing under exposure of a gating 515 nm light takes a very small value compared with X₁₁₁₁ and X₁₁₂₂. On the other hand, in the configuration of a probe beam and pump beams having linearly crossed polarizations and without gating light, the MO/PVA film generates a strong linearly polarized PC beam, so that X₁₂₂₁ takes a large value at 515 nm.     

基于PVA／AA光致聚合物的衍射光锥产生机理及其抑制

研究了以He—Ne激光器作为记录光源,以He-Ne、Nd：YAG和He-Cd激光器作为读出光源的亚甲基蓝敏化的PVA／AA体系光致聚合物的全息衍射光锥现象。衍射光锥现象的产生是由于入射光透过全息记录材料内部的不均匀结构或缺陷所产生的噪音光栅所致。运用Ewald球对此现象产生的机理进行了解释,利用全息光散射理论结合三角学...     

具有超小光斑点和高通光效率的AlGaAs 四面锥尖的模拟和优化

本文我们利用时域有限差分方法研究和比较了四种类型探针的光发射斑点和通光效率，在这些探针中，全镀薄金属银膜的AlGaAs 四面锥尖可提供最高的通光效率和单个近场光斑点。探针镀有3 nm银膜并利用波长800 nm入射光照射是提供高通光效率和超小光斑点的优化条件，高通光效率和超小光斑点的光探针使我们能实现超高密度光存储。     

Nonlinear refraction and photoinduced birefringence in chlorophosphonazo I doped polymer thin films

The nonlinear refraction and photoinduced birefringence of chlorophosphonazo I (CPA I ) doped PVA thin films were investigated. The single-beam Z-scan measurement showed that CPA I doped PVA thin film possessed a large value of nonlinear refractive index (n₂=1.82×10⁻¹² cm²/W) under a pulse 532 nm excitation, and the mechanism accounting for the process of nonlinear refraction was discussed in term of resonant electronic effect. Moreover, fast and stable molecular reorientation was observed when investigating the photoinduced birefringence of CPA I doped PVA thin film with a CW 532 nm laser as pump light and a CW 650 nm laser as probe light.     

BR-D96N薄膜共线全息图像存储实验研究

摘要:     利用一种生物光致变色材料—基因突变菌紫质BR-D96N薄膜的光致变色特性,实现了可擦写式共线全息图像存储实验.对于光密度为3.0的BR-D96N薄膜,在700 mW/cm2的记录光强下（波长为632.8 nm,物光、参考光光强比为约1:1.2）,全息图建立的最佳曝光时间约为3s,最佳再现光强约为50 mW/cm2,全息图寿命约为10 min.实验表明：共线全息存储技术光学系统简单,系统体积小,受存储环境的影响低,并能够实现高密度存储|同时也实验验证了BR-D96N薄膜具有响应速度快,感光灵敏度高,擦写次数高,稳定耐用,使用方便等优点,可以作为一种较灵敏的可擦写共线全息记录介质.     

White light micrograting multiplexing for high density data storage

Recording of multiplexed microholographic gratings with improved recording volume for high density optical data storage is proposed and demonstrated. By using a hybrid diffractive-refractive objective lens with extended depth of focus, we have achieved a recording beam size of approximately 1 microm and a focal depth of 20 microm. Multiple gratings corresponding to spectral lines within the 400-650 nm spectral band have been successfully multiplexed in a single recording spot or pit of size 1.25 microm on a DuPont photopolymer film using a white light source along with narrowband filters or dispersion elements, thus demonstrating the storage of multiple bits in a single pit. Simultaneous readout of multiple bits in a single storage pit is accomplished with a microspectrometer-type readout head using a white light source.     

Stretched exponential kinetics for photoinduced birefringence in azo dye doped PVA films

We fabricated azo dye (methylorange) doped poly vinyl alcohol (MO/PVA) thin films and measured the photoinduced birefringence (PIB) kinetics for several pump beam intensities and for various MO concentrations by using the pump-probe technique. A novel approach to explain the transient behaviors of the photoinduced anisotropy is presented by employing an empirical stretched exponential time response in the course of the trans-cis-trans photoisomerization of azo molecules and is compared with the experimental data, showing excellent agreement. The stretched exponent is estimated to be β = 0.34 ± 0.04, revealing amorphous nature of the MO/PVA system.     

数字显微全息中二次项相位误差的补偿

针对预放大式数字离轴显微全息技术中二次项相位误差,提出一种基于单幅全息再现的补偿方法.该方法是在显微物镜后焦平面处实现该相位误差的数学补偿,相位误差补偿过程具有调整参量单一化的优点.同时,利用显微物镜的后焦平面上物点特征实现了最佳再现距离的自动判断.该文以相位光栅为实验样本,对该方法进行了实验例证,实验结果验证了本文所提出二次项相位误差的补位误差的补偿方法的正确性和有效性.     

Improved phase hologram design for generating symmetric light spots and its application for laser writing of waveguides

The improved method for calculation of a phase hologram and its application to laser writing of waveguides with a spatial light modulator are presented. It was found that the amplitude and phase distributions of light spots generated by a phase hologram can be distorted compared to those of a focused single beam. The distortion of light spots could be reduced by adding a simple constraint, in which light intensities around a light spot should be as small as possible, to the conventional calculation method of a phase hologram. It was also demonstrated that the improved calculation method can be considered essential for laser writing of waveguides.