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中国物理学会期刊

不依赖激发光偏振方向的芯帽异构二聚体

CSTR: 32037.14.aps.71.20211381

Core-cap heterodimer independent of polarization direction of excitation light

CSTR: 32037.14.aps.71.20211381
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  • 各向异性贵金属纳米结构所特有的表面增强电场和近红外性能在纳米光电和生医传感等领域具有重要的应用, 但是其最佳光学性能的激发受限于结构姿态与光电场偏振方向的匹配. 本文基于芯帽颗粒特有的两个表面等离子体共振模式, 提出引入补偿结构, 利用二聚体结构间的局部表面等离子体共振耦合作用补偿电场偏转时缺失的近红外性能, 实现解除对激发光偏振方向的依赖关系. 基于有限元法数值求解了光与三维复杂异构二聚体作用后的电磁场分布, 分析了芯帽-芯壳异构二聚体间的作用模式, 从理论上明确了补偿结构去除偏振依赖的机理. 补偿后, 芯帽异构二聚体可在任意姿态下产生稳定的近红外高吸收性能, 在传感、成像、药物释放与光热疗法中具有广泛的应用潜力.

     

    The plasmonic anisotropic nanostructure possesses the enhanced surface electric field and unique optical properties in near-infrared spectrum, thus it has potential applications in nano-optoelectronics and medical sensing. To obtain the best property, the excitation polarization normally needs to match the orientation of the structure. The strong polarization dependence, however, greatly limits the excitation efficiency. In this work, a patchy structure is introduced to release the dependence of polarization. In the proposed method here in this work, the lost properties due to unmatched polarizations are compensated for by the plasmonic resonance coupling between the patch and capped structure in the heterozygous dimer. By overlapping the two modes at the same wavelength, the absorption keeps rather stable undisturbed status during the variation of incident polarization. This work focuses on the theoretical exploration of the feasibility. Electromagnetic field in the interaction between light and heterozygous dimer is essential before extinction coefficient is calculated. The field of the model is obtained by solving Maxwell equations through using the finite element method. The numerical calculation presents a good understanding of the mechanism of the plasmonic interactions in the dimer, based on which the nanostructure with optimized configuration parameters can achieve the stable and high absorption in the near infrared wavelength.

     

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