Abstract Distinctively narrow and asymmetric line shape Fano resonances arise due to resonant interactions of sub-radiant and super-radiant modes in plasmonic nanostructures and metamaterials. A number of recent experimental studies have shown unique opportunities provided by highly dispersive Fano resonances in biosensing applications. However, there is limited understanding of Fano resonant optical response to biomolecular accumulation. Here, we introduce a phenomenological model that can precisely describe the intricate nature of the Fano resonances in plasmonic nanohole arrays and provide unambiguous physical insights into biosensing experiments. Using rigorous electromagnetic simulations and experimental measurements as benchmarking tools, we show that the non-trivial contribution of molecular accumulation to Fano resonant plasmonic response can be incorporated as a mechanical loading effect in a coupled-oscillator model. Quite remarkably, our phenomenological approach captures the complex spectral response of the Fano resonance profile and asymmetric linewidth broadening upon molecular accumulation. Furthermore, in strong agreement with our experimental measurements, we show that our parameterized​ model has predictive power in fine tuning the Fano resonant extraordinary light transmission lineshape using structural design parameters without resorting to electromagnetic simulations. Our phenomenological model provides a general analytical method that can be adapted to understand biomolecular detection measurements in different plasmonic and metamaterial systems.

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Fano 共振生物传感的机制：等离子体振荡器的机械负载

摘要 由于等离子体纳米结构和超材料中亚辐射和超辐射模式的共振相互作用，会产生明显窄且不对称的线形 Fano 共振。最近的一些实验研究表明，高度分散的 Fano 共振在生物传感应用中提供了独特的机会。然而，对 Fano 共振光学响应对生物分子积累的理解有限。在这里，我们引入了一种现象学模型，该模型可以精确描述等离子体纳米孔阵列中 Fano 共振的复杂性质，并为生物传感实验提供明确的物理见解。使用严格的电磁模拟和实验测量作为基准工具，我们表明，分子积累对 Fano 共振等离子体响应的重要贡献可以作为机械负载效应合并到耦合振荡器模型中。非常值得注意的是，我们的现象学方法捕获了 Fano 共振剖面的复杂光谱响应和分子积累时不对称线宽的增宽。此外，与我们的实验测量结果非常一致，我们表明我们的参数化模型在使用结构设计参数微调 Fano 共振非凡光传输线形状方面具有预测能力，而无需求助于电磁模拟。我们的现象学模型提供了一种通用的分析方法，可用于理解不同等离子体和超材料系统中的生物分子检测测量。