共查询到20条相似文献,搜索用时 31 毫秒
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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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Spühler GJ Krainer L Innerhofer E Paschotta R Weingarten KJ Keller U 《Optics letters》2005,30(3):263-265
We report on a simple diode-pumped passively mode-locked Er:Yb:glass laser generating transform-limited 1536-nm solitons of 255-fs duration with a repetition rate of 50 MHz and average power of 58 mW. We also discuss timing jitter and the trade-off between short pulses and high output power in these lasers. 相似文献
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The emission spectra of calcium sulphide phosphors activated with bismuth, thulium, and both together are studied in the spectral range of 4000 Å to 8000 Å. The results indicate resonance transfer of excitation energy from Bi to Tm. Sensitizer to sensitizer transfer also appears to be appreciable. A plausible energy level diagram is proposed to explain the sensitization mechanism. 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
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The possibility of the occurrence of laser phenomena in the DCEL of thin films of ZnS:Cu:Nd:Cl, designed for display purposes, has been investigated. Evidence of stimulated emission at ~ 1080 nm has been found in both DCEL and cathodoluminescence emission of the films and has been attributed to a tendency to population inversion involving the energy level and a sub-level of the energy level. In addition, the expected directional nature of the stimulated emission has been shown to be present at the higher applied voltages. 相似文献