Specifics of scattering and radiation from sparse and dense dielectric meta-surfaces
Specifics of scattering and radiation from sparse and dense dielectric meta-surfaces
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DOI：
10.1063/1.5087422
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发表时间：
2019-04
影响因子：
3.2
通讯作者：
S. Jamilan;G. Semouchkin;N. Gandji;E. Semouchkina
中科院分区：
文献类型：
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作者：
S. Jamilan;G. Semouchkin;N. Gandji;E. Semouchkina
由纳米级硅颗粒组成的超表面被认为是未来亚波长厚度平面器件的潜在低损耗介质，能够实现许多光学功能，包括光束转向、聚焦和全息。先前的研究揭示了在Kerker条件下从硅超表面提供定向散射的机会，并预测在特定几何形状的粒子中偶极磁和电共振重叠时获得显著增强的散射强度。虽然硅超表面通常由密集阵列表示，但谐振器之间的相互作用在他们的分析中经常被忽略，通常使用超材料概念，假设阵列的响应可以由单个“元原子”的响应来表示。在这项工作中，我们研究了介电超表面中的合作共振现象，包括单粒子内的电和磁共振之间的相互作用以及阵列中谐振腔间的相互作用。首先，我们分析了单个谐振器从球体变为圆柱体，再变为圆盘时的响应变化，特别是描述了共振重合时电偶极子模式和磁偶极子模式形成的细节。然后，考虑了阵列中的现象，包括阵列对谐振腔响应的影响以及填充密度对超表面响应的影响。我们证明了密集的填料引起共振、横向耦合和共振场积分的强烈变化，影响了来自超表面的散射和辐射。所得结果对于理解介电超表面响应的复杂性、指导其设计以及散射和辐射控制具有重要意义。由纳米级硅颗粒组成的超表面被认为是未来亚波长厚度平面器件的潜在低损耗介质，能够实现许多光学功能，包括光束转向、聚焦和全息。先前的研究揭示了在Kerker条件下从硅超表面提供定向散射的机会，并预测在特定几何形状的粒子中偶极磁和电共振重叠时获得显著增强的散射强度。虽然硅超表面通常由密集阵列表示，但谐振器之间的相互作用在他们的分析中经常被忽略，通常使用超材料概念，假设阵列的响应可以由单个“元原子”的响应来表示。在这项工作中，我们研究了介电超表面中的合作共振现象，包括单粒子内的电和磁共振之间的相互作用以及共振间的相互作用。
Metasurfaces composed of nanosized silicon particles are considered prospective low-loss media for future planar devices with subwavelength thickness, capable of realizing many optical functionalities, including beam steering, focusing, and holography. Previous studies revealed an opportunity to provide directional scattering from silicon metasurfaces at Kerker’s conditions and projected obtaining significantly enhanced intensity of scattering at overlapping of dipolar magnetic and electric resonances in particles at their specific geometries. Although silicon metasurfaces are usually represented by dense arrays, interactions between resonators are often neglected in their analysis, which typically uses metamaterial concepts, assuming that responses of arrays can be represented by responses of single “meta-atoms.” In this work, we investigate cooperative resonance phenomena in dielectric metasurfaces, including interactions between electric and magnetic resonances within single particles and inter-resonator interactions in arrays. First, we analyze the transformation of the responses of single resonators, when their shape changes from a sphere to a cylinder, and then to a disk, and, in particular, describe the specifics of the formation of electric and magnetic dipole modes at a coincidence of resonances. Then, phenomena in arrays are considered, including the effects of arraying on resonator responses and the effects of packing density on metasurface responses. We demonstrate that dense packing causes strong changes of resonances, transverse coupling, and integration of resonance fields, affecting scattering and radiation from metasurfaces. The obtained results are important for understanding the complexity of responses of dielectric metasurfaces and provide guidance for their design and for scattering and radiation control.Metasurfaces composed of nanosized silicon particles are considered prospective low-loss media for future planar devices with subwavelength thickness, capable of realizing many optical functionalities, including beam steering, focusing, and holography. Previous studies revealed an opportunity to provide directional scattering from silicon metasurfaces at Kerker’s conditions and projected obtaining significantly enhanced intensity of scattering at overlapping of dipolar magnetic and electric resonances in particles at their specific geometries. Although silicon metasurfaces are usually represented by dense arrays, interactions between resonators are often neglected in their analysis, which typically uses metamaterial concepts, assuming that responses of arrays can be represented by responses of single “meta-atoms.” In this work, we investigate cooperative resonance phenomena in dielectric metasurfaces, including interactions between electric and magnetic resonances within single particles and inter-resonat...