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951.
L. Gao X. P. Yu 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(4):403-409
We derive expressions for the effective nonlinear susceptibility
tensors for both the second harmonic generation (SHG) and induced
third harmonic generation (THG) of nonlinear composite materials,
in which nondilute coated particles with radial dielectric
anisotropy are randomly embedded in the linear host. Two types of
coated particles are considered. The first is that the core
possesses a second order nonlinear susceptibility and the shell is
linear and radially anisotropic, while the second is that the
core is linear with radial anisotropy and the shell has a second
order nonlinear susceptibility. We observe greatly enhanced SHG
and THG susceptibilities at several surface plasmon resonant
frequencies. For the second model, due to the coating material
being metallic, there exists two fundamental resonant frequencies
ωc1 and ωc2, whose difference
ωc2-ωc1 is strongly dependent on the interfacial
parameter and the radial dielectric anisotropy. Furthermore, in
both systems, the adjustment of the dielectric anisotropy results
in larger enhancement of both SHG and induced THG susceptibilities
at surface plasmon resonant frequencies than the corresponding
isotropic systems. Therefore, both the core-shell structure and
the dielectric anisotropy play important roles in determining the
nonlinear enhancement and the surface resonant frequencies. 相似文献
952.
晶粒间界相对纳米Nd_2Fe_(14)B各向异性和矫顽力的影响 总被引:1,自引:0,他引:1
本文采用立方晶粒结构模型研究了晶粒间界相对纳米硬磁材料各向异性和矫顽力的影响.结果表明:晶粒间界相减弱了交换耦合作用.当晶粒尺寸D为定值时,随着晶粒间界相厚度d的增加,晶粒平均各向异性单调增加,而材料的有效各向异性Keff、矫顽力单调减小.我们计算的矫顽力随晶粒尺寸的变化与相关理论和实验结果基本一致. 相似文献
953.
In this paper, a new channel drop filter in two dimensional photonic crystals with mirror cavities is proposed. In the structure,
three cavities are used. One is used for a resonant tunneling-based channel drop filter. The others are used to realize reflection
feedback in the bus waveguide, which consists of a point defect micro-cavity side-coupled to a waveguide. The simulation results
by using the finite-difference time-domain method conclude 98% output efficiency. 相似文献
954.
955.
956.
介质层厚对含负折射率介质Bragg微腔的影响 总被引:1,自引:0,他引:1
研究了介质层厚对含负折射率介质一维光子晶体Bragg微腔的缺陷模和双稳态的影响.在中心频率附近将传输矩阵各矩阵元采用泰勒级数展开并取一级近似,得到了缺陷模频率与介质层厚的关系式及品质因子公式.研究结果表明:一级近似法能很好地解释中心频率附近介质层厚对缺陷模频率的影响.理想Bragg微腔结构的缺陷模品质因子最大;递增正折射率介质层厚和增大缺陷层介质层厚、递减负折射率介质层厚及同时等量递减正和负折射率介质层厚,均可使缺陷模红移,双稳态阈值降低. 相似文献
957.
LUO En & LI WeiHua Department of Applied Mechanics Engineering Sun Yat-sen University Guangzhou China 《中国科学G辑(英文版)》2007,50(3):370-378
According to the basic idea of classical yin-yang complementarity and modern dual-complementarity, in a simple and unified way proposed by Luo, some basic principles in the dynamic theory of viscoelastic materials with voids can be estab- lished systematically. In this paper, an important integral relation in terms of con- volutions is given, which can be considered as the generalized principle of virtual work in mechanics. Based on this relation, it is possible not only to obtain the principle of virtual work and the reciprocal theorem, but also to derive systemati- cally the complementary functionals for the eight-field, six-field, four-field simpli- fied Gurtin-type variational principles and the potential energy-functional for the two-field one in the dynamic theory of viscoelastic materials with voids by the generalized Legendre transformations given in this paper. Furthermore, with this approach, the intrinsic relationship among various principles can be explained clearly. 相似文献
958.
报道了通过宏观测量偶氮聚合物光致异构效应,及其引起的光学各向异性变化,讨论了一种影响偶氮聚合物顺反异构效应的有效途径。在偶氮高分子聚合物中,添加了不同浓度的Ag纳米粒子,采用了波长为442nm的He-Cd偏振激光为激发光源,当Ag纳米粒子掺杂质量浓度为0.12μg/ml的时候,激发了薄膜样品中Ag纳米粒子的等离子体共振效应,增强了粒子周围纳米尺度的电磁场强度,相当程度上提高了偶氮聚合物光致异构的转换效率;另外,研究了不同的取代基同纳米Ag粒子的相互作用对光致异构效应的影响,探讨了一种能够有效地控制光致异构效应的方法。 相似文献
959.
采用传统陶瓷烧结工艺,在无压还原气氛下低温制备出透明性良好的掺Yb3+氧化镧钇透明激光陶瓷,测试了其在室温下的吸收光谱、发射光谱和荧光寿命.结果表明,掺Yb3+氧化镧钇透明激光陶瓷的吸收系数随着Yb3+掺杂浓度的增加而增大,最强吸收峰974nm处的吸收截面为0.90~1.12×10-20 cm2;主发射峰1 032 nm和1 075 nm处的发射截面分别为1.05×10-20 cm2和0.87×10-20 cm2; Yb3+掺杂浓度为5at.%时荧光寿命为1.38 ms,并随Yb3+掺杂浓度的增加而减小;当Yb3+掺杂浓度超过10at.%时,样品中存在严重的浓度猝灭.产生浓度猝灭的原因是高掺杂时离子间存在合作上转换和能量转移. 相似文献
960.
J. F. Zhou Z. Chen L. B. He C. H. Xu L. Yang M. Han G. H. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):283-286
InSb nanostructures have been synthesized by the use of
gas aggregation process. Nanoparticles with different shapes are obtained by
controlling the growth and deposition temperature of the InSb nanoclusters.
Triangular nanocrystals are commonly observed when the clusters are
extracted from the condensation chamber of the source and deposited on the
room temperature substrate at high vacuum. When the deposition is performed
inside the condensation chamber at high temperature near the melting point
of bulk InSb, nanoparticles formed on the substrate surface show several
kinds of 3-dimensional morphologies, such as triangular or rectangular
prisms, as well as hexagonal tablets. Keeping the same conditions for the
cluster source operation and deposition, after long time growth, nanorods
with hexagonal and quadrangular cross sections are formed through
vapor-liquid-solid (VLS) process. The origin of the difference on the
morphologies and shapes of the nanostructures is attributed to the
anisotropic growth of InSb, which is temperature dependent. 相似文献