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861.
测试了不同掺杂浓度和样品厚度下掺铒磷酸盐和碲酸盐玻璃的吸收光谱、荧光光谱和荧光寿 命,计算了Er3+离子在1.53 μm处的吸收截面(σa)、发射截面(σ e)、自发辐射跃迁概率(Arad)、辐射跃迁寿命(τrad) 、以及辐射跃迁量子效率(η)等光谱参数.讨论了荧光俘获效应对掺铒磷酸盐和碲酸盐玻璃 光谱性质及光谱参数的影响.结果表明即使在铒离子低掺杂浓度(0.1 mol% Er2O 3)下,荧光俘获效应也普遍存在于掺铒玻璃材料中,使得荧光寿命(τf sub>)和荧光半高宽(FWHM)随样品的厚度和铒离子掺杂浓度增加而增大,导致碲酸盐和磷酸 盐玻璃中τf分别增加11%—37%和6%—17%,FWHM分别增加15%—64%和11%—55% ,使得掺铒玻璃材料的放大品性参数(σe×FWHM) 也相应被估高.由于铒离子在 碲酸盐玻璃中在1.53 μm处吸收和发射截面重叠面积较大,加之铒离子在前者基质中的发射 截面高于后者,使得掺铒碲酸盐玻璃中的荧光俘获效应高于磷酸盐玻璃.
关键词:
荧光俘获
铒离子
碲酸盐玻璃
磷酸盐玻璃 相似文献
862.
Jinyao Liu Zhihua Nie Yong Gao Alex Adronov Huaming Li 《Journal of polymer science. Part A, Polymer chemistry》2008,46(21):7187-7199
Covalent functionalization of alkyne‐decorated multiwalled carbon nanotubes (MWNTs) with a well‐defined, azide‐derivatized, thermoresponsive diblock copolymer, poly(N,N‐dimethylacrylamide)‐poly(N‐isopropylacrylamide) (PDMA‐PNIPAM) was accomplished by the Cu(I)‐catalyzed [3 + 2] Huisgen cycloaddition. It was found that this reaction could simultaneously increase the molecular size and bonding density of grafted polymers when PDMA‐PNIPAM micelles were employed in the coupling system. On the other hand, attachment of molecularly dissolved unimers of high‐molecular weight onto the nanotube resulted in low‐graft density. The block copolymer bearing azide groups at the PDMA end was prepared by reversible addition–fragmentation transfer polymerization, which formed micelles with a diameter of ~40 nm at temperatures above its critical micelle temperature. Scanning electron microscopy was utilized to demonstrate that the coupling reaction was successfully carried out between copolymer micelles and alkyne‐bearing MWNTs. FTIR spectroscopy was utilized to follow the introduction and consumption of alkyne groups on the MWNTs. Thermogravimetric analysis indicated that the functionalized MWNTs consisted of about 45% polymer. Transmission electron microscopy was utilized to image polymer‐functionalized MWNTs, showing relatively uniform polymer coatings present on the surface of nanotubes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7187–7199, 2008 相似文献
863.
Changfeng Xue Junxiang Nie Wenchang Tan 《Nonlinear Analysis: Theory, Methods & Applications》2008,69(7):2086-2094
Modified Darcy’s law for fractional generalized Burgers’ fluid in a porous medium is introduced. The flow near a wall suddenly set in motion for a fractional generalized Burgers’ fluid in a porous half-space is investigated. The velocity of the flow is described by fractional partial differential equations. By using the Fourier sine transform and the fractional Laplace transform, an exact solution of the velocity distribution is obtained. Some previous and classical results can be recovered from our results, such as the velocity solutions of the Stokes’ first problem for viscous Newtonian, second grade, Maxwell, Oldroyd-B or Burgers’ fluids. 相似文献
864.
865.
针对四波混频技术在军事上的应用,计算了经过大气畸变的弱激光参与的简并四波混频过程,得到了共轭反射率的表示式,讨论了反射光与信号光近似100%共轭所需的条件。 相似文献
866.
智能大屏幕显示屏的设计与制作 总被引:2,自引:0,他引:2
本文对大屏幕电子显示屏提出了新的显示控制方法,有利于发挥单片机的功能和新的功能扩展。本设计特别适合于中小型显示屏的制作,具有成本低、修改画面内容改变方便等特点。 相似文献
867.
Yongchun Wen Cong Wang Ying Sun Man Nie Liang Fang Yongjun Tian 《Solid State Communications》2009,149(37-38):1519-1522
The temperature-dependent magnetization, lattice, and transport properties of Mn3Sn1−xGexC (0≤x≤0.5) compounds are systematically investigated. The Mn–Mn atomic distance decreases as Ge content is increased, and the transition temperature from ferromagnetic (or ferrimagnetic) to paramagnetic state decreases too. Mn3SnC has a large magnetovolume effect (MVE). However, Ge-doping in Mn3SnC gradually reduces the MVE, till the MVE disappears. Whether there is an abnormal lattice change or not, there always exists an anomalous increase in resistivity near the magnetic phase transition point with decreasing temperature. 相似文献
868.
The study of millimeter-wave low sidelobe linear arrays with time modulation technique is presented in this paper. Special
emphasis is on the realization of low sidelobes with uniform amplitude excitations, which are easier for the practical implementation.
Two types of time modulated linear arrays with uniform amplitude excitations, namely, the variable aperture size (VAS) linear
arrays with optimized time sequences and the linear arrays with optimized random time sequences were studied. The optimized
time sequences are obtained via the differential evolution (DE) algorithm and the genetic algorithm (GA). Many factors that
affect the array performance are discussed.
Supported by the National Natural Science Foundation of China (No. 60571023), the SRF for ROCS, SEM, and the innovative Research
Team Program of UESTC, China. 相似文献
869.
In this paper, we consider the multi-asset optimal investment-consumption model: a riskless asset and d risky assets. when the initial time is t?0, for a proportional transaction costs and discount factors, we proof that the value function of the model is a unique viscosity solution of a Hamilton-Jacobi-Bellman (HJB) equations. 相似文献
870.