PRIMALIGHT, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Nanotechnology. 2017 Mar 10;28(10):104001. doi: 10.1088/1361-6528/aa593d. Epub 2017 Feb 1.
One of the most fascinating possibilities enabled by metamaterials is the strong reduction of the electromagnetic scattering from nanostructures. In dielectric nanoparticles, the formation of a minimal scattering state at specific wavelengths is associated with the excitation of photonic anapoles, which represent a peculiar type of radiationless state and whose existence has been demonstrated experimentally. In this work, we investigate the formation of anapole states in generic dielectric structures by applying a Fano-Feshbach projection scheme, a general technique widely used in the study of quantum mechanical open systems. By expressing the total scattering from the structure in terms of an orthogonal set of internal and external modes, defined in the interior and in the exterior of the dielectric structure, respectively, we show how anapole states are the result of a complex interaction among the resonances of the system and the surrounding environment. We apply our approach to a circular resonator, where we observe the formation of higher-order anapole states, which are originated by the superposition of several internal resonances of the system.
超材料最吸引人的可能性之一是能够大大减少纳米结构的电磁散射。在介电纳米粒子中，在特定波长下形成最小散射态与光子反极子的激发有关，光子反极子代表一种特殊类型的无辐射态，其存在已通过实验证明。在这项工作中，我们通过应用 Fano-Feshbach 投影方案来研究一般介电结构中反极子态的形成，这是一种广泛用于研究量子力学开放系统的通用技术。通过将结构的总散射表示为内部和外部模式的正交集，这些模式分别在介电结构的内部和外部定义，我们展示了反极子态是系统和周围环境的共振之间复杂相互作用的结果。我们将我们的方法应用于一个圆形谐振器，在那里我们观察到高阶反极子态的形成，这些态是由系统的几个内部共振的叠加产生的。
