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研究了声波在二维声子带隙材料中的传输特性,把声子带隙材料作为一个散射体进行处理.在远场近似下(kr≥1),计算了声波在有限范围内声子带隙材料中的传输系数,得到了与带结构符合很好的计算结果, 相似文献
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Transmission Loss due to Modes Conversion Caused by Random Surface Imperfections in Left-Handed-Material Slab Waveguides 下载免费PDF全文
Based on the orthogonality relations among the modes in left-handed-material (LHM) slab waveguides (SWGs), we derive the coupled equations among the modes caused by imperfect surfaces, and compute the transmission loss due to mode conversion. The computation shows that the transmission loss is very large, which is due to three facts: (1) there exist slow waves in the LHM SWG, whose electric field is mainly distributed in the surface; (2) the absence of fundamental node-less modes, so the fundamental modes have a node, whose electric field is also mainly distributed in the surface, and (3) the different focusing effects of the random RHM and LHM imperfections cause the electric field to suffer from severe deformations aggravated by the electric field distribution of the guided wave and the slow wave, which of course dissipates the power carried by the guided wave more severely. Therefore, we can safely conclude that the LHM SWG is unsuitable for transmitting the fundamental modes with a node. 相似文献
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全面计入电-声子耦合导致的热移位(其中包括~2T_1贡献的单声子项,Raman项,光学支项)与热膨胀导致的热移位,对MgO:Cr~(3+)与MgO:V~(1+)的R线热移位作了理论计算,结果与热移位、热膨胀系数,高压移位、声子谱与光谱、晶体密度、弹性常数与晶格常数等大量实验数据符合得很好.进而,将完全的d~3能量矩阵对角化,得到能谱与波函数,再通过电-声子相互作用矩阵元等一系列计算,从微观上算出单声子项的参量,结果与拟合实验得到的值符合得很好.结果表明:单声子项起主导作用(导致红移),而Raman项(导致
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根据掺稀土和过渡金属离子的晶场光谱热移位理论,光谱热移位应包括4部分贡献.利用波函数混合系数对其中作主要贡献的单声子项参量进行了理论计算,然后再对MgO:V2+的R线的热移位进行了拟合计算,计算结果与大量实验数据符合很好. 相似文献
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本文从电子径向波函数在加压下扩展的概念出发,进下考虑三角场效应,将B、C、Dq、ξ、δ等参量表示为线性压缩比x的函数,我们对红宝石的光谱移位进行了理论计算,所得结果与实验符合很好,本文研究表明:三角场效应在谱线的压力移位中起着重要的作用。 相似文献
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本文给出了一种新的生成技术,建立了一个新的生成解定理,根据此定理,可以由任何一个已知的静态真空解生成一个新的电磁真空解,并从Schwarzchild出发生成了一新解。 相似文献
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The Fibonacci piezoelectric superlattices(FPSs) with an external dc electric field is presented, in which the dc electric field can tune the bandwidth of polaritonic band gaps(PBGs) continuously and reversibly via the electrooptic effect. The absolute bandwidths of two major PBGs of the FPSs around ω= 7.5 GHz and ω = 12.5 GHz can be broadened from 0.022 GHz to 0.74 GHz and from 0.02 GHz to 0.82 GHz with the dc electric field increasing from 0 to 1.342 × 10~6 V/m, respectively. The corresponding relative bandwidths of the two major PBGs are widened from 0.28% to 9.2% and from 0.18% to 6.35%, respectively. The general mechanism for the bandwidth tunability is that the coupling strength between the lattice vibration and electromagnetic waves is capable of being altered by the dc electric field via the electro-optic effect. Thus the properties can be applied to construct microwave switchings or field tunable bulk acoustic filters. 相似文献
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在已有工作基础上,计入自旋—轨道相互作用,定量拟合计算了MgO:V ̄(2+)的压力移位,得到了一套较为可靠的高压参数,理论计算结果与实验符合很好。 相似文献