光致变色多阶游程光存储研究

多阶游程存储是一种不改变光学系统而显著提高光存储容量和数据传输率的新方法.介绍了光致变色多阶游程存储原理和实验系统.提出了基于光致变色原理的多阶游程存储数学模型，该模型反映了记录符反射率与曝光功率、曝光时间之间的非线性关系，并在此基础上确定了光致变色多阶游程存储的写策略.基于650nm光致变色材料进行了4阶游程存储的动态实验.结果表明，实验中采用的650nm光致变色材料可用于多阶游程存储，采用的写策略能够有效地使记录信道线性化，利于采用适合线性系统的信号处理方法. 关键词： 多阶游程 光致变色 光存储 写策略     

Material saturation in photopolymer holographic data recording and its effects on bit-error-rate and content-addressable search

Fourier transform of an amplitude modulated data page gives rise to high intensity at the zero-spatial frequency. Recording such high intensity requires a large-dynamic range on the part of the recording material and leads to material saturation. Moving the recording plane away from the Fourier plane is often used for spectrum uniformity and thereby improving the quality of reconstruction. In the present paper, we have investigated the effect of photopolymer material saturation on the bit-error-rate, the signal-to-noise ratio, and content-addressable search of a holographic data storage system. We have performed numerical simulation of the process of hologram recording and corresponding reconstruction, and show an improvement in the BER and the SNR values of the reconstructed data page for the defocused recording. A multi-layer thin-slice approach to take into account the thickness of recording material is used to simulate the volume hologram. The numerical simulation model can be used as an efficient tool for system optimization.     

Holographic testing of fluorescent photosensitive glass-ceramics

In this paper we investigate the holographic recording properties of the fluorescent photosensitive glass-ceramics. The materials described here, stable up to 400 °C, represent a substantial advancement in the development of long lifetime media for holographic data storage. A detailed physical-chemical characterization of the proposed material is presented. It is shown that volume holograms were obtained after the recording process using a continuum high power laser in an off-axis setup.     

近场光学在高密度存储中的应用

近场光学在高密度存储方面有着很大的潜力 ,使得近场光学存储近年来得到了广泛的关注。近场光学存储具有高密度大容量及可以利用许多已有相关技术等优点 ,预计近场光学存储密度能达到 7Gbit/ cm2 ;它还可以采用硬盘驱动器中的空气悬浮磁头技术和磁光存储中的技术等 ,使近场存储的研究和开发更加迅速。目前 ,近场光学存储主要有三种方案 :探针型方案、超分辨率近场结构、固体浸没透镜方案 ,这三种方案都是通过不同的方法缩小记录光斑来实现高密度的存储。介绍了近场光学存储的原理、研究现状及材料 ,并对三种近场存储方案的实现方法和发展概况作了详细的阐述 ,分析了这三种方案的优缺点     

Fabrication and characterization of poly(methyl methacrylate) photopolymer doped with 9,10-phenanthrenequinone (PQ) based derivatives for volume holographic data storage

We present our studies on the photopolymer of poly(methyl methacrylate) (PMMA) doped with 9,10-phenanthrenequinone based derivatives for volume holographic storage. By introducing different functional groups on the side-chain of 9,10-phenanthrenequinone molecule, the holographic characteristics of the material can be modified. The photoreaction involved with the holographic recording in the samples was investigated by measuring UV-Vis absorption spectrum and mass spectrum. The experimental results show that the similar behaviors were exhibited in these photopolymers. It is found that phase hologram recording in our PQ derivatives doped PMMA photopolymer involves a structure change of the quinone based molecule, which induces a strong change of the refractive index. Experimental characterizations on holographic data storage, including material sensitivity, dynamic range (M#) and bit-error-rate have been performed. We found that, by selecting appropriate functional groups, an improvement in sensitivity and M# for holographic data storage can be achieved.     

Analysis of temperature change effects on hologram recordingand a compensation method

For commercialization of holographic storage drives, the effects of temperature changes on holographic medium is critical. There has been no systematic study on the effect of temperature change on hologram recording properties. We believe that the monomer-diffusion speed and polymerization rate changes are critical for hologram-recording properties and estimate those parameters on each temperature using the photopolymer medium process simulation we have developed. We describe how these parameters affect actual recording properties such as sensitivity, M=# and so on. Moreover, we propose a method for compensating temperature changes, and confirm the success of this.     

Modeling high density microholographic data storage: Using linear, quadratic, thresholding and hard clipping material characteristics

Crosstalk related raw signal-to-noise ratio (SNR) and bit error rate (BER) of high density bitwise microholographic data storage is investigated by numerical modeling. Scattering and diffraction of light is calculated in non-paraxial scalar approximation. A multiple thin slice implementation of the perturbative volume integral equation is used, which can be easily parallelized. The effect of bit and track spacing, and the different local characteristics of the holographic recording material on the SNR, BER and diffraction efficiency are investigated. The results show that these lateral spacing parameters have much more effect on crosstalk noise than the number of layers. Using two-photon, thresholding or hard clipping materials generates less crosstalk noise at the same data density than a linear material, and the dynamic range of these materials can be used more effectively resulting in higher single microhologram diffraction efficiencies.     

Diffraction efficiency and signal-to-noise ratio of multiplexed volume phase holograms recorded in a photographic emulsion

The problems related to noise that arise during recording and reconstruction of holograms used in optical data storage or in massive optical interconnection systems are quite similar and can be analyzed in order to improve the quality of the images that these optical systems provide. In this paper, we will analyze noise in cases in which several coherent object waves are simultaneously stored in a phase recording material in a way that allows us to obtain information about the relationship that exists between the recording material and the number of waves that are being stored. The material used in this study is Agfa Gevaert 8E75 HD holographic film processed with a rehalogenating—type bleach bath without a fixation step. Additionally, we show experimentally that it is possible to holographically store more than 400 waves at the same time (in a coherent fashion) using the same storage geometry, with a signal-to-noise ratio larger than 20 and an average diffraction efficiency of 15%.     

GeSbTe 与 AgInSbTe 体系相变光盘的研究进展

自Ovshinsky把相变材料用于光存储以来 ,一大批具有可逆光存储性能的材料不断出现 ,其中研究较多的是GeSbTe和AgInSbTe两种体系 .文章着重介绍了利用这两种材料制成的相变光盘记录介质的微观结构特点 ,阐述了其晶化机理 ;同时 ,较详细地概述了光盘的堆栈结构及掺杂其他元素对相变光盘性能的影响 ,并对比说明了GeSbTe和AgInSbTe两种体系在蓝光记录方面的各自特点     

Multi-level optical data storage in a photobleaching polymer using two-photon excitation under continuous wave illumination

A multi-level recording method is implemented in a photobleaching polymer using two-photon excitation under continuous wave illumination. It is experimentally shown that information encoded with ten levels of darkness can be successfully stored. This multi-level bit optical data storage method is of importance in increasing the storage density of a recording material and the speed of data access.     

Permanent data recording in transparent materials by using a nanojoule-class pulse laser

We investigated data recording for permanent data storage using an ultrafast pulse laser with nanojoule-class pulse energy and megahertz-class repetition rate in transparent materials, and driveless reading based on a simple imaging system. A transparent ceramics called Lumicera®, manufactured by Murata Mfg. Co., Ltd., was used as the recording medium. Lumicera® has a lower modification threshold and a higher recording sensitivity than those of silica glass, namely, the medium previously studied. Structural modification in Lumicera® occurs by light exposure for 10 μs, suggesting that Lumicera® has potential for a recording speed of over 100 kbps. Data recorded in Lumicera® resists heating for 2 h at 1000 °C and is expected to have a lifetime of over 300 million years. Moreover, the data recorded in Lumicera® was successfully read with a reading system based on a smart phone.     

Digital holography at millimetre wavelengths

In this paper, we describe a method for wavefront reconstruction at millimetre wavelengths using off-axis holography, a frequently used image recording technique at visible wavelengths first demonstrated in the 1960’s. Millimetre radiation has been highlighted recently in the imaging of non-conducting materials and objects, which often show significant transparency at these long wavelengths, even though opaque at visible and infrared wavelengths. Holography provides a method for recording a lens-less image of an object thus reducing loss of spatial frequency information, which is important for obtaining maximum resolution at long wavelengths. An experimental arrangement based on a simple form of Fresnel off-axis holography is described, with the object illumination and reference beams derived using two radiating horn antennas fed by a single coherent source (a Gunn diode oscillator operating at 100 GHz – wavelength 3 mm) via a 3 dB cross-guide coupler. The process is discussed in the context of imaging and in the validation of millimetre wave radiation sources (horns). We show that the entire fields from these and other components can be analysed using computational optics with data derived from a single measurement obtained using inexpensive equipment.     

储热空间内支撑结构对相变结晶膨胀的影响

相变储能技术作为一种特殊的储能技术,可以将能量跨地域、跨时间储存.相变储能材料在蓄放热过程中,温度可以在一定范围内保持恒定不变,并且具有储热密度高、性能稳定、材料来源广泛、适用于各领域等优点,但应用过程中也存在一些比较棘手的问题.本文选取典型的水合盐八水氢氧化钡,针对其膨胀特性进行了实验研究及分析.实验中,在材料储能体...     

空调蓄冷材料研究现状及其新进展

分析了空调蓄冷材料研究现状及存在的一些问题 ,提出研制一种新型空调复合蓄冷材料 ,通过实验 ,分析该蓄冷材料的融点、融解热等热学性能。并通过实验研究寻找到了一种新型空调蓄冷材料 ,测试结果表明该蓄冷材料具有较高的相变潜热、适宜的相变温度和较好的热稳定性 ,因此可被应用于蓄冷空调系统中。     

输出绿光的上转换材料及紫外、可见图象存储和图象减法

研究了一种输出绿光的上转换材料,它能存储紫外和可见光(图象),并能将红外光学图象转换为可见光图象.用200μm厚的薄膜做了图象存储和图象减法的实验.实验结果表明,这种材料对光存储和光学信息处理应用具有很多有吸引力的优点,如:可擦除、可重写、高分辨、高速度、大的响应线性特性以及模拟和并行操作等.     

Multilevel read-only optical recording methods

The advantages of read-only storage is the predominance of optical recording relative to magnetic and other rewritable methods. Multilevel (ML) read-only technology has been a trend to improve the data capacity and transfer rate. Based on the principle and coding method of ML, this paper demonstrates some ML read-only recording methods, of which a new ML read-only recording is developed. This recording method integrates amplitude modulation achieved by the reaction mechanism of physics and chemistry of photoresist with the run-length-limited technology. The discs can be achieved using standard photoresist mastering and replication techniques with great compatibility to conventional binary read-only discs.     

超高密度电学信息存储研究进展

21世纪是经济信息化、信息数字化的高科技时代，信息的爆炸式增长及电子器件持续微型化的要求需要小断研究和开发更高仔储密度、更快响应速度、更长存储寿命及可反复读、写的材料和器件。在纳米／分子尺度上实现存储功能的超高密度信息存储已成为当前信息领域一个倍受关注的研究热点。本文从存储材料和技术角度介绍了基于电学双稳态的超高密度信息存储最新研究进展。     

二芳烯材料在重复擦写体全息存储中的应用研究

二芳烯材料是一种性能优异的光致色变材料,具有很好的抗疲劳性能,一般能重复擦写上万次,而不损失其性能。通过体全息光栅记录实验、角度复用体全息存储实验、重复擦写及强光记弱光读等实验,对二芳烯材料在重复擦写体全息存储中的应用进行了系统研究。由于二芳烯材料具有很高的折射率调制度(Δn=1.15×10-3)、可多次重复擦写、强光记弱光读的准非易失等性能,在可重复擦写的体全息存储中具有广阔的应用前景。     

Long-time-storage mechanism for Tm:YAG in a magnetic field

We obtained a long-time-storage mechanism for spectral features in thulium ions doped into YAG by applying a magnetic field that splits the electronic ground state. We show experimentally that the storage time can be more than 30 s, which is 3 orders of magnitude longer than that of the metastable state that normally is used for information storage in this material. Level splitting and storage lifetimes for various magnetic field strengths of as much as 5 T were investigated. This storage mechanism will be relevant in the many coherent transient-based signal-processing schemes in which Tm:YAG is being used, and we demonstrate long-time storage in a basic data storage application.     

自组装有机分子薄膜的可逆超高密度信息存储

信息技术的迅速发展对信息存储密度提出了越来越高的要求，采用自组装方法研究了有机分子4’-氰基-2，6-二甲基-4-羟基偶氮苯（4’cyano-2，6-dimethyl-4-hydroxy azobenzene）的成膜特性．通过在扫描隧道显微镜的针尖和基底之间加脉冲电压在薄膜上进行信息点的写入，得到了直径为1．8nm的信息点，并分析了信息点形成的机理．