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比较了掺Fe量相同的两种晶体Fe :LiNbO3和Zn :Fe :LiNbO3的光折变性能 ,并且给出了Zn :Fe :LiNbO3晶体光电导和衍射效率与入射总光强的关系 .在Zn :Fe :LiNbO3晶体二波耦合实验中观察到衍射效率随记录时间的增长先增加 ,达到饱和后又逐渐减小的自擦除现象 ,并采用光折变双载流子四陷阱模型对该现象加以解释 .在此基础上选择合适的曝光时序 ,利用角度复用技术在该晶体中进行体全息存储 ,并在同一点上存入 30幅图像 相似文献
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比较了掺Fe量相同的两种晶体Fe:LiNbO3和Zn:Fe:LiNbO3的光折变性能,并且给出了Zn:Fe:LiNbO3晶体光电导和衍射效率与入射总光强的关系.在Zn:Fe:LiNbO3晶体二波耦合实验中观察到衍射效率随记录时间的增长先增加,达到饱和后又逐渐减小的自擦除现象,并采用光折变双载流子四陷阱模型对该现象加以解释. 在此基础上选择合适的曝光时序,利用角度复用技术在该晶体中进行体全息存储,并在同一点上存入30幅图像.
关键词:
双载流子四陷阱模型
自擦除
电子-空穴竞争
角度复用 相似文献
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连续光条件下对LiNbO3:Fe:Mn晶体全息存储性能的理论研究 总被引:1,自引:0,他引:1
以双中心模型为基础,在低光强连续光条件下研究了LiNbO3:Fe:Mn晶体在稳态情况下的非挥发双光双步全息存储性能.采用数值方法.通过比较双中心模型中深(Mn2 /Mn3 )、浅(Fe2 /Fe2 )能级之间所有可能的电子交换过程,发现由隧穿效应引起的深浅能级之间直接电子交换过程对LiNbO3:Fe:Mn晶体总的空间电荷场大小起着决定性的作用.同时.这一电子交换过程对晶体非挥发全息存储性能也起着至关重要的作用.此外.通过相同实验条件下LiNbO3:Fe:Mn晶体与近化学比LiNbO3:Fe晶体总的空间电荷场的比较,显示LiNbO3:Fe:Mn晶体在低抽运光和高记录光光强条件下有着比近化学比LiNbO3:Fe晶体更佳的伞息存储性能. 相似文献
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掺Ce,Fe系列LiNbO3晶体光折变效应光存储特性 总被引:9,自引:4,他引:5
研究了系列Ce:Fe掺杂以及不同后处理态(生长态、还原态和氧化态)铌酸锂晶体的透过率光谱和光折变全息存储特性。实验结果表明单掺Ce铌酸锂晶体具有较好的图像存储质量和较宽的透过率光谱范围,二波耦合增益相对较低;高掺杂铌酸锂样品的透过率光谱范围较窄,光折变二波耦合增益较低。晶体的后处理对铌酸锂样品的光折变特性影响明显,双掺Ce:Fe还原态铌酸锂晶体具有较高的二波耦合增益;氧化态样品具有较大的透过率光谱范围;还原态样品具有较大的光折变二波耦合增益特性。实验结果还表明在同种样品中难于同时获得大的二波耦合增益和图像存储质量。 相似文献
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以双中心模型为基础,在低光强连续光条件下研究了LiNbO3∶Fe∶Mn晶体在稳态情况下的非挥发双光双步全息存储性能。采用数值方法,通过比较双中心模型中深(Mn2+/Mn3+)、浅(Fe2+/Fe3+)能级之间所有可能的电子交换过程,发现由隧穿效应引起的深浅能级之间直接电子交换过程对LiNbO3∶Fe∶Mn晶体总的空间电荷场大小起着决定性的作用。同时,这一电子交换过程对晶体非挥发全息存储性能也起着至关重要的作用。此外,通过相同实验条件下LiNbO3∶Fe∶Mn晶体与近化学比LiNbO3∶Fe晶体总的空间电荷场的比较,显示LiNbO3∶Fe∶Mn晶体在低抽运光和高记录光光强条件下有着比近化学比LiNbO3∶Fe晶体更佳的全息存储性能。 相似文献
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用于双色全息存储(Fe,Cu)∶LiNbO3晶体的参量优化计算 总被引:1,自引:0,他引:1
在确定Cu在LiNbO3晶体中对应于365 nm和633 nm的激发系数、复合系数、光伏系数的基础上,采用龙格库塔(Runge-Kutta)数值方法理论研究了双掺杂(Fe,Cu)∶LiNbO3晶体的深浅能级的掺杂组分比、氧化还原状态对双色全息存储的记录灵敏度和动态范围的影响,并探讨了同时取得尽可能大的灵敏度和动态范围的晶体条件。结果表明,为了同时得到较大的记录灵敏度和动态范围,在实际应用中选用浅能级掺杂浓度为5.0×1025m-3,深能级掺杂浓度为3×1024~3×1025m-3之间的弱氧化晶体是合适的。 相似文献
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Zn:Fe:LiNbO3晶体全息存储性能研究 总被引:7,自引:7,他引:0
以提拉法生长Zn(1mol%):Fe:LiNbO3, Zn(4mol%):Fe:LiNbO3,Zn(7mol%):Fe:LiNbO3晶体.Zn:Fe:LiNbO3晶体随着Zn2+浓度的增加,抗光致散射能力增加,Zn(7mol%):Fe:LiNbO3晶体抗光致散射能力比Fe:LiNbO3晶体提高两个数量级以上.测试了Zn:Fe:LiNbO3晶体衍射效率、响应时间.以Zn(7mol%):Fe:LiNbO3晶体作为存储元件,Zn(4mol%):Fe:LiNbO3晶体作为位相共轭镜,进行全息关联存储试验.试验结果显示出成像质量好、图像清晰完整、噪音小等优点.研究了Zn:Fe:LiNbO3晶体全息存储性能增强的机理.Zn(4mol%):Fe:LiNbO3晶体具有全息存储性能最佳的综合指标. 相似文献
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利用基于密度泛函理论的第一性原理,研究了Cu:Fe:Mg:LiNbO3晶体及对比组的电子结构和光学特性.研究显示,单掺铜或铁铌酸锂晶体的杂质能级分别由Cu 3d轨道或Fe 3d轨道贡献,禁带宽度分别为3.45和3.42 eV;铜、铁共掺铌酸锂晶体杂质能级由Cu和Fe的3d轨道共同贡献,禁带宽度为3.24 eV,吸收峰分别在3.01,2.53和1.36 eV处;Cu:Fe:Mg:LiNbO3晶体中Mg^2+浓度低于阈值或高于阈值(阈值约为6.0 mol%)的禁带宽度分别为2.89 eV或3.30 eV,吸收峰分别位于2.45 eV,1.89 eV或2.89 eV,2.59 eV,2.24 eV.Mg^2+浓度高于阈值,会使吸收边较低于阈值情况红移;并使得部分Fe^3+占Nb位,引起晶体场改变,从而改变吸收峰位置和强度.双光存储应用中可选取2.9 eV作为擦除光,2.5 eV作为读取和写入光,选取Mg^2+浓度达到阈值的三掺晶体在增加动态范围和灵敏度等参量以及优化再现图像的质量等方面更具优势. 相似文献
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E.A. Neppiras 《Ultrasonics》1984,22(1):25-28
Acoustic cavitation has been an active area of research for at least 30 years and interest in the subject shows no sign of diminishing. Cavitation may occur whenever high intensity ultrasound is applied to liquids, for example in such important applications as sonar, industrial processing and bio-medical research. Future issues will carry a series of articles reviewing the physics and technology of acoustic cavitation, each contributed by a well-known specialist. The present introductory article is a preface to the series, covering background history, explaining the scope of the subject and defining terms in common use. Also included is a list of the major sources of reference presently available, in the form of books, reviews and collections of papers. 相似文献
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The radiothermoluminescence characteristics have been studied for a number of (ZnS:CdS::Ag:Ni:Co) phosphors, with various cobalt impurity contents, after exposure to90Sr beta-rays at room temperature. Thermoluminescent spectra show a peak wavelength of 7000 Å, which remains unchanged with increase in cobalt concentration. Thermoluminescence curves exhibit a single well-defined peak appearing at temperatures far above room temperature. This peak shifts to lower temperatures with increasing cobalt content. The relation between thermoluminescence response and dose is linear over the dose range of 1 to 500 rads. Thermoluminescence measurements made after storing the irradiated phosphor for 48 hours in dark have revealed an information loss of 4% over this storage period. The radiothermoluminescence characteristics, storage capacity and storage stability of these sulphide phosphors compete reasonably with those of lithium fluoride over the dose range of 1 rad to 500 rads. 相似文献
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Fourier transform profilometry: : a review 总被引:4,自引:0,他引:4
Fourier transform profilometry is one of the popular non-contact 3-D measurement methods, where a Ronchi grating or sinusoidal grating is projected onto a diffuse three-dimensional surface, and the resulting deformed grating image is detected by a CCD camera and processed by a computer. This method requires only one frame (or two frames) of the deformed fringe pattern in some algorithms to retrieve the surface of measured object, so it has obvious advantage for real time data acquisition and 3-D measurement of dynamic process. In this paper, we review some algorithms in FTP, discuss some important problems, including frequency spectra overlapping, phase unwrapping, sampling, and 3-D measurement of dynamic process. With the development of computer hardware and software and availability of high-resolution image grabber, FTP method will be a promising one for acquiring 3-D data of object, and more and more researchers pay attention to it. 相似文献
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分别测量了Er YCOB晶体和ErYb YCOB晶体的室温吸收光谱.讨论了Yb3+离子对Er3+离子的敏化作用. 相似文献
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H. S. Peng X. J. Huang Q. H. Zhu X. D. Wang K. N. Zhou X. F. Wei X. M. Zeng L. Q. Liu X. Wang Y. Guo D. H. Lin B. Xu L. B. Xu X. L. Chu X. M. Zhang 《Laser Physics》2006,16(2):244-247
Based on chirped pulse amplification technology, we have built a Ti:sapphire laser system, called SILEX-I (superintense laser for experiments on extremes), at CAEP, which consists of three stages with 5-, 30-, and 300-TW outputs, respectively. The first and the second stages work at 10 Hz, while the third works at single shot. Pulse durations of 30 fs have been obtained by installing an acousto-optic programmable dispersive filter (AOPDF) to compensate for the spectral gain narrowing in the regen. By taking a number of advanced measures for spatial beam control, such as spatial beam shaping, relay-imaged propagation, precise alignment of compressor gratings, and OAP, near-diffraction limited focal spots (FWHM) have been obtained. Focused intensities are calculated at (1–3) × 1020 W/cm2 with an f/2.2 OAP.SILEX-I has shown an excellent stability and reliability in operations for applications since its completion and will soon be able to operate at 500 TW. 相似文献