Han Aoxue, Moloney Jerome V, Babicheva Viktoriia E
James C. Wyant College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA.
Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA.
J Chem Phys. 2022 Mar 21;156(11):114104. doi: 10.1063/5.0082005.
Periodic nanoparticle arrays have attracted considerable interest recently since the lattice effect can lead to spectrally narrow resonances and tune the resonance position in a broad range. Multipole decomposition is widely used to analyze the role of the multipoles in the resonance excitations, radiation, and scattering of electromagnetic waves. However, previous studies have not addressed the validity and accuracy of the multipole decomposition around the lattice resonance. The applicability of the exact multipole decomposition based on spherical harmonics expansion has not been demonstrated around the lattice resonance with the strong multipole coupling. This work studies the two-dimensional periodic arrays of both plasmonic and dielectric nanospheres and compares the multipole decomposition results with the analytic ones around their lattice resonances. We study both the effective polarizabilities of multipoles and the scattering spectra of the structures. The analytical results are calculated from the coupled dipole-quadrupole model. This study demonstrates that the exact multipole decomposition agrees well with the numerical simulation around lattice resonances. Only a small number of multipoles are required to represent the results accurately.
周期性纳米粒子阵列最近引起了相当大的关注，因为晶格效应可导致光谱窄共振，并在很宽的范围内调节共振位置。多极分解被广泛用于分析多极在电磁波共振激发、辐射和散射中的作用。然而，以往的研究尚未涉及晶格共振附近多极分解的有效性和准确性。基于球谐展开的精确多极分解在具有强多极耦合的晶格共振附近的适用性尚未得到证明。这项工作研究了等离子体和介电纳米球的二维周期性阵列，并将多极分解结果与它们晶格共振附近的解析结果进行了比较。我们研究了多极的有效极化率和结构的散射光谱。解析结果是由耦合偶极 - 四极模型计算得出的。这项研究表明，精确的多极分解在晶格共振附近与数值模拟结果吻合良好。只需要少量的多极就能准确地表示结果。
