The field confinement of plasmonic systems enables spectral tunability under structural variations or environmental perturbations, which is the principle for various applications including nanorulers, sensors, and color displays. Here, we propose and demonstrate that materials with anomalous dispersion, such as Ge in the visible, improve spectral tunability. We introduce our proposal with a semianalytical guided mode picture. Using Ge-based film (Ag/Au)-coupled gap plasmon resonators, we implement two architectures and demonstrate the improved tunability with single-particle dark-field scattering, ensemble reflection, and color generation. We observe three-fold enhancement of tunability with Ge nanodisks compared with that of Si, a normal-dispersion material in the visible. The structural color generation of large array systems, made of inversely fabricated Ge–Ag resonators, exhibits a wide gamut. Our results introduce anomalous material dispersion as an extra degree of freedom to engineer the spectral tunability of plasmonic systems, especially relevant for actively tunable plasmonics and metasurfaces.

中文翻译：

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通过异常材料色散增强等离子光谱的可调谐性

等离子体系统的现场限制可在结构变化或环境扰动下实现光谱可调性，这是包括纳米尺，传感器和彩色显示器在内的各种应用的原理。在这里，我们提出并证明具有异常色散的材料（例如可见光中的Ge）可改善光谱可调性。我们以半分析引导模式图片介绍我们的建议。使用基于Ge的薄膜（Ag / Au）耦合的间隙等离子体激元谐振器，我们实现了两种架构，并展示了单粒子暗场散射，整体反射和颜色生成的改进的可调谐性。我们观察到，Ge纳米盘的可调谐性比可见光中的正常分散材料Si的可调谐性提高了三倍。大型阵列系统的结构颜色生成，由反向制造的Ge-Ag谐振器制成的色域广。我们的结果引入了异常的材料色散，作为设计等离子体系统的光谱可调性的额外自由度，尤其与主动可调的等离子体和超表面有关。