Optical resonances in nanostructures can be harnessed to produce a wide range of structural colors. Conversely, the analysis of structural colors has been used to clarify the nature of optical resonances. Here, we show that silicon nanowire (NW) pairs can display a wide range of structural colors by controlling their radiative coupling. This is accomplished by exciting a series of Fabry–Pérot-like modes where light is repeatedly scattered between two NWs. These modes are beyond the expectation from the conventional chemical bonding model under a quasi-electrostatic approximation, in which only bonding and antibonding modes can be formed in a pair system through modal hybridization. The additional eigenmodes found in a two-resonator system originate from the nonlinear, frequency-dependent coupling strength derived from the radiative nature of low-Q resonators. The Fabry–Pérot modes can be tuned across the entire visible frequency range by varying the distance between two NWs, leading to what we believe is a new type of universal building blocks that can provide structural color within a subwavelength footprint. The presented results pave the way toward the design and usage of highly tunable resonances that exploit the radiative coupling of high-index nanostructures.

中文翻译：

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纳米线对的结构颜色超出了键合和反键合模型

可以利用纳米结构中的光学共振产生广泛的结构颜色。相反，结构颜色的分析已用于阐明光学共振的性质。在这里，我们表明，硅纳米线（NW）对可以通过控制其辐射耦合来显示多种结构颜色。这是通过激发一系列类似于Fabry–Pérot的模式来完成的，其中光在两个NW之间反复散射。这些模式超出了常规化学键合模型在准静电近似下的期望，在准静电近似中，通过模态杂交只能在成对系统中形成键合和反键合模式。在两个谐振器系统中发现的其他本征模式源自非线性的，与频率相关的耦合强度，该耦合强度源自于低谐振频率的辐射特性。Q谐振器。通过改变两个NW之间的距离，可以在整个可见频率范围内调整Fabry-Pérot模式，从而导致我们相信是一种新型的通用构件，可以在亚波长范围内提供结构颜色。提出的结果为利用高折射率纳米结构的辐射耦合的高度可调共振的设计和使用铺平了道路。