Herein, a refractive-index sensor is theoretically proposed, which comprises metal-insulator-metal waveguide and single rectangle cavity without a long side (RCWALS). The propagation characteristics were analyzed by finite element method. Compared with the contrastive structure, the designed single RCWALS structure has better transmission spectra and stronger resonance and supports Fano resonance. The effects of the structural parameters on sensing characteristics were investigated. Mode 1 of single RCWALS structure has better performance parameter, which is the best sensitivity of 1840 nm/RIU with a figure of merit of 51.11. Additionally, three derived structures are presented, which are composed of MIM waveguide and two RCWALS in different positions. They have lower sensitivity but better figure of merit, and provide more detection positions. The designed structures, which are greatly simple, can potentially apply to nanophotonics.

中文翻译：

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基于Fano共振的结构简单的折射率纳米传感器

在此，理论上提出了一种折射率传感器，它包括金属-绝缘体-金属波导和单个无长边矩形腔（RCWALS）。传播特性通过有限元方法进行分析。与对比结构相比，设计的单RCWALS结构具有更好的透射光谱和更强的共振，并支持Fano共振。研究了结构参数对传感特性的影响。单RCWALS结构的模式1具有更好的性能参数，其最佳灵敏度为1840 nm/RIU，品质因数为51.11。此外，还提出了三种衍生结构，它们由不同位置的 MIM 波导和两个 RCWALS 组成。它们具有较低的灵敏度但较好的品质因数，并提供更多的检测位置。