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We have analysed theoretically the polarization and dielectric constant of uniaxial ionic crystals,including the effect of the nonlinear interactions between ions.The spectrum of polaritons(coupling modes of photons and optical phonons) under nonlinear interactions was developed.A new branch of dispersion relations emerges in the original frequency gap. 相似文献
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LI Yong LIU Xu-Feng 《理论物理通讯》2005,44(8)
We investigate the transient phenomenon or property of the propagationof an optical probe field in a medium consisting of many A-type three-level atoms coupled to this probe field and a classical driven field. We observe a hidden symmetry and obtain an exact solution for this light propagation problem by means of the spectral generating method. This solution enlightens us to propose a practical protocol implementing the quantum memory robust for quantum decoherence in a crystal. As a transient dynamic process this solution also manifests an exotic result that a wave-packet of light will split into three packets propagating at different group velocities. It is argued that “super-luminal group velocity“ and “sub-luminal group velocity“ can be observed simultaneously in the same system. This interesting phenomenon is expected to be demonstrated experimentally. 相似文献
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表面等离激元的聚焦与波导增强 总被引：1，自引：0，他引：1
近年来,表面等离激元学（plasmonics）已经形成一个新的学科热点.电子在金属与介质界面的集体振荡行为形成一种元激发——表面等离激元（surface plasomon polariton,SPP）.由于其具有特殊的耦合与传播性质,与SPP相关的器件设计与应用成为目前纳米光子学领域的国际前沿研究方向.文章介绍了利用微... 相似文献
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A polarization-insensitive unidirectional spoof surface plasmon polariton(SPP) coupler mediated by a gradient metasurface is proposed. The field distributions and average Poynting vector of the coupled spoof SPPs are analyzed. The simulated and experimental results support the theoretical analysis and indicate that the designed gradient metasurface can couple both the parallel-polarized and normally-polarized incident waves to the spoof SPPs propagating in the same direction at about 5 GHz. 相似文献
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通过解析求解简单极化激元模型的Pancharatnam相位, 研究了温度、耦合强度、声子与光子频率差、平均光子数等对其演化的影响. 结果表明,Pancharatnam相位随时间振荡,且振荡频率和振荡波形随时间变化,这种变化随着温度升高和耦合强度、声子与光子频率差增加而加大. 系统Pancharatnam相位随时间的演化在平均光子数较小时表现比较有规律,但随着平均光子数的增加,它趋于混沌化.关键词：极化激元Pancharatnam 相位Mach-Zehnder干涉仪相干态 相似文献
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对实验测量的PbB4O7晶体样品的太赫兹(1012Hz)光谱、拉曼光谱以及红外—可见—紫外光谱进行了分析.在0.25—2.5THz波段介电函数随频率变化曲线ε(ν)出现共振型尖峰.四方面的分析表明PbB4O7晶体中存在软光学声子:1)介电函数随频率的变化曲线ε(ν)满足LST(Lyddane-Sachs-Teller)关系;2)在共振峰的频率附近(3.10THz)有很强的拉曼散射峰;3)吸收系数随频率的变化曲线α(ν)满足极化激元的特征;4)透过晶体的光子的色散关系ν(k)发生断开的畸变.PbB4O7晶体中存在软光学声子的意义在于,在满足产生极化激元的条件下,透过晶体的光子的频率会发生劈裂,分为升高和降低的两支,有可能利用这种原理来改变光子的频率. 相似文献
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基于闪锌矿晶体中受激电磁耦子散射产生可调谐太赫兹波的理论研究 总被引：2，自引：0，他引：2
基于受激电磁耦子散射原理,采用已报道的利用非线性光学参量振荡方法产生可调谐太赫兹波的实验条件作为理论分析的实验模型,以GaAs,GaP, InP,ZnTe晶体为代表,计算分析了在闪锌矿晶体中参量振荡产生太赫兹波的吸收、增益特性,对输出THz波的调谐特性给出了详尽分析.分析太赫兹波高效耦合输出的腔型结构,并与掺氧化镁铌酸锂晶体组成的太赫兹波参量振荡器做对比.关键词：太赫兹波太赫兹波参量振荡电磁耦子闪锌矿晶体 相似文献
40.
In this paper, four optical filter topologies based on metal–insulator–metal waveguides are proposed and the designed structures are investigated numerically using finite-difference timedomain method. Triangular-shaped adjunctions have been added to the filter structures to improve their transmission spectrum. These improved structures consist of air as the insulator and silver as the metal. The relative permittivity of metal has been described via the Drude,Drude–Lorentz, and Palik models. The first filter's transmission spectrum shows an acceptable transmittance. In the second optimized filter, the transmission spectrum has been improved. The transmittance spectrum can be tuned through adjusting the edge of the triangle in these four optimized filters. As a result, the bandwidths of resonance spectra can be adjusted. The theory of such tapered structures will be investigated by the tapered transmission line and will be solved with the transfer matrix method. This method shows a better performance and higher transmission efficiency in comparison with the basic structures. On the other hand, the final filter has been chosen as the best one because of its hexagonal resonator. The main reason for having a better result is due to a longer interaction length in comparison with the circular resonator. This in turn creates much better energy coupling and results in higher transmission. 相似文献