Nanoparticle lattices with bases: Fourier modal method and dipole approximation
Nanoparticle lattices with bases: Fourier modal method and dipole approximation
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DOI：
10.1103/physrevb.102.045432
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发表时间：
2020-07-31
影响因子：
3.7
通讯作者：
Gippius, Nikolay A.
中科院分区：
文献类型：
--
作者：
Fradkin, Ilia M.;Dyakov, Sergey A.;Gippius, Nikolay A.
利用周期性结构，如光子晶体和亚表面，在纳米尺度上进行光操纵是很常见的。基于电磁场傅里叶分解的傅里叶模态法(FMM)是考虑它们并设计有效光学器件的最广泛使用的计算方法之一。然而，计算含有小夹杂物的周期结构往往是一项困难的任务，因为它们会引起许多应该考虑的高k(平行)谐波。本文考虑具有基的小粒子晶格(复晶胞)，并利用离散偶极近似构造了它们的散射矩阵。然后，为了考虑复杂的层状结构，在FMM中实现了这些矩阵。我们通过将所提出的混合方法应用于格子来展示该混合方法的性能，该格子将左、右圆偏振入射光路由到沿相反方向传播的导模。通过与有限元计算的频谱比较，验证了该方法的精度。这种方法速度快、精度高，可以在合理的时间内以很高的分辨率计算随角度变化的光谱，从而可以分辨出其他方法所不能观察到的窄线。
The utilization of periodic structures such as photonic crystals and metasurfaces is common for light manipulation at nanoscales. One of the most widely used computational approaches to consider them and design effective optical devices is the Fourier modal method (FMM) based on Fourier decomposition of electromagnetic fields. Nevertheless, calculating periodic structures with small inclusions is often a difficult task since they induce lots of high-k(parallel to) harmonics that should be taken into account. In this paper, we consider small-particle lattices with bases (complex unit cells) and construct their scattering matrices via discrete dipole approximation. Afterwards, these matrices are implemented in FMM for consideration of complicated layered structures. We show the performance of the proposed hybrid approach by its application to a lattice, which routes left and right circularly polarized incident light to guided modes propagating in opposite directions. We also demonstrate its precision by spectra comparison with finite-element method calculations. The high speed and precision of this approach enable the calculation of angle-dependent spectra with very high resolution in a reasonable time, which allows resolving narrow lines unobservable by other methods.