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Evolution of polarization singularities accompanied by avoided crossing in plasmonic system 下载免费PDF全文
Yi-Xiao Peng 《中国物理 B》2023,32(1):14201-014201
The evolution of polarization singularities supported in a one-dimensional periodic plasmonic system is studied. The lateral inversion symmetry of the system, which breaks the in-plane inversion symmetry and up-down mirror symmetry simultaneously, yields abundant polarization states. A complete evolution process with geometry for the polarization states is traced. In the evolution, circularly polarized points (C points) can stem from 3 different processes. In addition to the previously reported processes occurring in an isolated band, a new type of C point appearing in two bands simultaneously due to the avoided band crossing, is observed. Unlike the dielectric system with a similar structure which only supports at-$\varGamma$ bound states in the continuum (BICs), accidental BICs off the $\varGamma$ point are realized in this plasmonic system. This work provides a new scheme of polarization manipulation for the plasmonic systems. 相似文献
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在局域源所产生的电磁场中,以波长为特征长度可以引入两个重要概念:近场和远场。准静态场是另一重要概念。回溯人类对电磁场的认识过程,从一开始分立的静态电/磁场,到麦克斯韦方程组所描述的完整的运动电磁场,经历了认识的飞跃。有限的时间频率是运动电磁场的重要特征量。本文以不同维度的辐射源为例,分析了其产生的近场和远场,区分了两种产生近场的机制,并阐述了近场和静态场的关系。最后,本文以介质平板中的法布里-珀罗共振和金属颗粒的表面等离激元共振为例,揭示了不同维度下近场对能量储存的贡献及其与不同维度微腔的品质因子巨大差异的直接关系。 相似文献
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利用有限元方法研究了理想导体薄膜中齿状孔阵列在微波频段的超透射现象.齿状结构的引入使得孔阵列的透射谱发生红移,在更深的亚波长区实现全透射.近场分析表明分布在齿状孔上的局域态对红移起了关键作用.研究发现单个齿孔支持人工局域表面等离激元多极子模式,与超透射相关的是偶极子模式.该研究方案可以推广到红外与太赫兹频段. 相似文献
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Bound states in the continuum in metal—dielectric photonic crystal with a birefringent defect 下载免费PDF全文
Hongzhen Tang 《中国物理 B》2022,31(10):104209-104209
By using the difference of the band structure for the TE and TM waves in the metal—dielectric photonic crystals beyond the light cone and the birefringence of the anisotropic crystal, a one-dimensional photonic system is constructed to realize the bound states in the continuum (BICs). In addition to the BICs arising from the polarization incompatibility, the Friedrich—Wintgen BICs are also achieved when the leaking TM wave is eliminated due to the destructive interference of its ordinary and extraordinary wave components in the anisotropic crystal. A modified scheme favorable for practical application is also proposed. This scheme for BICs may help to suppress the radiation loss in the metal—dielectric photonic crystal systems. 相似文献
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