Lattice Resonances in Optical Metasurfaces With Gain and Loss
Lattice Resonances in Optical Metasurfaces With Gain and Loss
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DOI：
10.1109/jproc.2019.2939396
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发表时间：
2020-05-01
影响因子：
20.6
通讯作者：
Koenderink, A. Femius
中科院分区：
文献类型：
--
作者：
Kolkowski, Radoslaw;Koenderink, A. Femius
与活性介质耦合的强散射物体的周期性晶格在应用纳米光子学中至关重要，它可以作为具有定制发射特性的发光超表面，并有望为测试新颖的物理概念和实现前所未有的光整形功能提供一个有吸引力的平台。我们概述了半解析格林函数方法与埃瓦尔德晶格求和应用于研究具有增益和损耗的共振纳米散射体周期性阵列中的表面晶格共振。该理论旨在作为具有增益的等离子体晶格和超表面的最小模型：复杂性最小，但足够丰富，可以成为自洽、完全延迟的多重散射模型。它能够包括任意方向和排列的电和/或磁点偶极子之间的电磁相互作用，考虑到这些相互作用的延迟和张量性质，并包括辐射阻尼。它可以访问远场可观测值（反射/透射）以及引导模式的光子能带结构。同时，与常用的紧束缚或准静态模型相反，它不违反光学定理。在将晶格格林函数形式主义扩展到包括晶胞中的增益和损耗之后，我们证明了有源有损等离子体阵列中宇称时间（PT）对称性破缺的影响：例外点的出现、光子带的非平凡拓扑、发散的有效晶胞极化率以及PT破缺相中的自旋极化。
Periodic lattices of strongly scattering objects coupled to active media are of central importance in applied nanophotonics, serving as light-emitting metasurfaces of tailored emission properties and promising an attractive platform for testing novel physical concepts and realization of unprecedented light-shaping functions. We provide an overview of the semianalytical Green function method with Ewald lattice summation applied to the investigation of surface lattice resonances in periodic arrays of resonant nanoscatterers with gain and loss. This theory is meant as a minimal model for plasmonic lattices and metasurfaces with gain: minimal in complexity, yet sufficiently rich to be a self-consistent, fully retarded multiple scattering model. It enables to include the electromagnetic interactions between electric and/or magnetic point dipoles of arbitrary orientation and arrangement, taking into account retardation and tensorial nature of these interactions and including radiation damping. It gives access to the far-field observables (reflection/transmission), as well as to the photonic band structure of guided modes. At the same time, it does not violate the optical theorem, as opposed to the commonly used tight-binding or quasi-static models. After extending the lattice Green function formalism to include gain and loss in the unit cell, we demonstrate the effects of parity-time (PT) symmetry breaking in active-lossy plasmonic arrays: the emergence of exceptional points, nontrivial topology of photonic bands, diverging effective unit-cell polarizability, and spin polarization in the PT-broken phase.