标题要闻

1.高性能超大容量三维光折变全息材料及存储器的研制——光折变三维全息信息存储器是一种涉及多个学科的综合产品。其性能优化及其商品化依赖于存储器所用的CCD等光电设备及步进电机等机械设备。该产品覆盖存储材料、存储密度提高、存储器小型化、误码抑制等多个方面，为全息存储器的成果转化奠定了基础。2.北京四维图新导航信息技术有限公司实施的卫星导航电子地图高技术产业化示范工程通过验收——自主创新引领导航电子地图远行，标志着制约我国导航产业发展的导航电子地图瓶颈问题得到解决。3.中国又多了两颗“金钉子”——“金钉子”(…     

A+r激光光折变全息照相存储器的研究

分析了激光光折变全息照相存储器的工作原理，并对它的存储容量进行了理论计算，同时将这种存储器的性能指标与现行光盘进行比较。     

“三维全息光存储器”研制成功

由南开大学光子学中心承担的国家“８６３”高技术项目“光折变三维光子海量存储材料双掺铌酸锂晶体及其（固定式）存储器”研究，日前通过国家级鉴定．这表明我国在大容量信息存储器研制开发领域取得新进展． 随着超能力计算机、核算网络及多媒体技术的高速发展，大规模数据库的建设势在必行，现有的存储器及转移速率已不能满足发展的要求．目前，各国积极研制开发的“三维全息光存储器”，其存储容量将比现有存储器的存储容量高１０００多倍，信息转移速率也比原来的高几千倍．而这种新型存储器面世并走向成熟的关键，是寻找理想的三维全…     

LiNbO3晶体中光折变光栅的各向异性衍射

光折变晶体中光栅的各向异性衍射可用来提高光折变存储器读出信号的信噪比。本文通过极化率张量对LiNbO3晶体中光栅形成和衍射的偏振特性进行了理论分析,并关重对光栅矢量与晶体光轴共面的情形进行了实验研究。观察到的各向异性衍射读出角度的测量结果与理论计算相符。     

新型光折变晶体Mn:YAP研究进展

Mn：YAP晶体是近年来发现的一种新型光折变晶体,在三维全息存储方向有广阔的应用前景。总结了Mn：YAP的晶体结构、光谱特征及其光折变模型,分析了它的优点和不足,并对其研究方向提出了设想。     

光折变空间光孤子

回顾了光折变孤子的相关研究及最新进展,描述了光折变孤子的形成及特性,分析了光折变孤子形成的理论机理,展示了光折变孤子的相互作用,说明了光折变孤子的应用价值及缺陷.     

光折变二波耦合增益振荡

1 引言 光折变二波耦合增益振荡在光学长度—频率转换仪、实时波前反转、激光腔中的畸变修正、光计算及相关存储器等中有广泛的应用。就其振荡器的类型可分为自泵浦相位共轭振     

光学自增强效应与衍射效率的提高

利用含时光折变双光耦合方程数字模拟计算了掺铁铌酸锂晶体中双光耦合的动态过程,分析了空间电荷场及其位相、光折变光栅位相等光折变参量的变化过程,解释了光折变自增强效应,提出了提高光折变光栅衍射效率的有效方法．     

量子阱光折变器件

量子阱光折变器件光折变器件可用于一系列应用，特别是图象处理，但受到折变效应速度缓慢和需要较高强度光的限制。普渡大学Ｄ．Ｎｏｌｔｅ和贝尔实验室的Ａ．Ｇｌａｓｓ正努力发展克服光折变器件中某些问题的半绝缘多量子阶，并于最近对薄膜光折变器作了综述。块状材料和...     

KTN晶体中新的光折变现象

自光折变效应出现以来,许多科学家在这一领域进行了大量的研究,提出了一些模型对光折变现象进行了解释,最有代表性的是苏联科学家Kukhtarey等人提出的单个载流子和单个光折变中心的带传输模型,尽管带传输模型在解释部分光折变效应有成功之处,但仍不能对某些光折变现象进行令人满意的解释。我们首次在KTN晶体中观察到了在一     

Photorefractive optics in three-dimensional digital memory

To exceed the capacity limitation of the surface-recording method of current optical data storage, the third dimension is introduced with photorefractive materials. Photorefractive materials are suitable for three-dimensional data storage in conjunction with nonlinear optical systems such as the two-photon absorption process of the material for recording and the confocal laser-scanning system for reading. I will describe the systems and the materials for three-dimensional digital memory with the experimental results for read-only memory with photopolymer, erasable memory with a lithium niobate crystal and rewritable memory with photochromic organic materials. The comparison between photorefractive digital three-dimensional memory with conventional holographic three-dimensional memory and near-field memory is also discussed in terms of dynamic range, noise, recording density, and accessibility     

Confocal readout of three-dimensional data bits recorded by thephotorefractive effect under single-photon and two-photonexcitation

In three-dimensional optical bit data storage, data bits can be recorded as a result of the change in refractive index in photorefractive and photochromic materials under single-photon and two-photon excitation by a high numerical-aperture objective. In principle, these recorded data bits can be read out using reflection confocal microscopy because such a microscope exhibits an optical sectioning property for three-dimensional imaging. In this article, the conditions are described under which three-dimensional data bits recorded by the photorefractive effect under single-photon and two-photon excitation in these materials can be read in reflection confocal microscopy. The effect of the refractive-index mismatch between a volume recording medium and its immersion medium on these conditions is also considered     

Electro-optic tunable filter

Theoretical analysis of electro-optic tunable filters (EOTFs) using colinear and noncolinear interactions is presented. An effective electro-optic coefficient is derived for various classes of birefringent crystal. We propose to implement the EOTF using the nonlinear photorefractive effect. The photorefractive EOTF can be used for optical storage.     

Send a hologram [photorefractive materials]

As computers and the Internet become faster and faster, more and more information is transmitted, received, processed, and stored everyday. The demand for high-speed, large-capacity information systems is pushing scientists and engineers to explore all possible approaches, including electrical and optical means. Photorefractive materials and devices are becoming viable alternatives for information systems. Photorefractive materials, including traditional electrooptic photorefractive crystals as well as photopolymers and photosensitive glasses, have demonstrated their potential in information systems. In this article we describe several applications of various photorefractive materials in information storage, processing, and communication systems. Specifically, we briefly discuss the applications of the traditional electrooptic photorefractive crystals and photopolymers in volume holographic data storage (VHDS) and information processing. Then, we discuss our recent works on the applications of photopolymers, holographic polymer dispersed liquid crystals (H-PDLC), and photosensitive glasses in photonic devices for optical fiber communications.     

多重全息存储中曝光均匀性的研究

本文分析了光折变晶体多重全息存储中扇形效对光栅写入时间常数的影响和写入光耦合光栅振幅的影响,给出了两种因素影响下角度编码多重全息存储中时间递减曝光法的计算公式和方法,该计算和通常的有所不同。     

光折变晶体中反射型多重全息图的 布喇格偏移

从理论上研究了光折变反射型全息光栅的布喇格偏移问题,着重研究了布喇格偏移随写入时间的演变。实验证实了反射型光栅确实存在布喇格偏移现象,验证了布喇格偏移量随写入时间的演变与折射率调制度随写入时间的演变有相同的规律。实验表明,在大容量全息存储中,曝光时间很短的全息图可以在记录角度读出,而布喇格偏移的影响可以忽略     

Optical signal processing using photorefractive effect

Novel applications of photorefractive effect to optical signal processing are proposed and demonstrated. The applications of two-wave mixing (2-WM) in a bulk photorefractive crystal include logic operations and cross connect. Photorefractive crystal waveguide (PCW) is another primary concern. Holographic storage of Fourier transformed image in PCW and its application to optical neural network, two-dimensional array of PCW as a storage device, phase conjugate mirror using PCW, and structural consideration of PCW for efficient 2-WM are investigated. In the experiments,LiNbO ₃ andBaTiO ₃ waveguides are used.BaTiO ₃ waveguide will be tested here for the first time. In a long-term prospect, all these technologies will eventually find important roles in optical signal processing.     

The use of the photorefractive effect for comprehensive three-dimensional local measurements of electrical and thermal parameters of silicon structures

The photorefractive effect was studied as a basis for developing a new method of contactless comprehensive mapping of electrical and thermal properties of silicon structures. The possibility of making three-dimensional local measurements of the charge carrier mobility and lifetime and the thermal diffusivity in a single technological cycle at any point of the sample volume was shown. A new technique for the simultaneous measurement of all these parameters was developed.     

高密度光学信息存储的最新进展

本文介绍高密度光信息存储的最新进展,阐述在光折变材料上全息存储的多波长、多角度、多相位记录和读取方法,噪声的改善和全息图的寿命;双光子吸收在聚焦光束扫描存储技术中的应用;近场光学记录方法,光纤探针的研制以及孔径介质间距控制。最后讨论了光存储材料的发展。