In this paper, a novel, to the best of our knowledge, surface plasmon resonance (SPR) fiber biosensor is theoretically proposed to detect the surrounding refractive index based on a Stampfli-type photonic quasi-crystal fiber with one air hole coated gold thin film. Surface plasmon polaritons (SPPs) at the metal/dielectric interface are excited by the orbital angular momentum (OAM) mode (other than Gaussian mode) that propagates very robustly along the fiber with helical phase, facilitating the energy transformation of OAM mode to SPP mode and then realization of the typical resonant loss peak. The proposed OAM-SPR fiber sensor exhibits a refractive index sensitivity of 4466.5 nm/RIU and a resolution of ${2.3} \times {{1}}{{{0}}^{- 5}}$ RIU in a broad refractive index range from 1.36 to 1.435. Numeric results show that both structure parameters of the fiber and thickness of the gold layer influence sensing performance as the phase matching condition varies. This work offers theoretical guidance for the design of an OAM-SPR fiber biosensor and has great potential applications in sensing bio-molecular and bio-chemical liquids.

中文翻译：

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基于光子准晶体光纤的用于折射率传感的 OAM 模式激发表面等离子体共振

在本文中，据我们所知，一种新颖的表面等离子体共振 (SPR) 光纤生物传感器被理论上提出来检测基于 Stampfli 型光子准晶体光纤的周围折射率，该光纤带有一个气孔涂层金薄膜. 金属/电介质界面处的表面等离子体激元 (SPP) 被轨道角动量 (OAM) 模式（高斯模式除外）激发，该模式沿具有螺旋相位的光纤非常稳健地传播，促进 OAM 模式到 SPP 模式的能量转换然后实现典型的谐振损耗峰值。所提出的 OAM-SPR 光纤传感器的折射率灵敏度为 4466.5 nm/RIU，分辨率为${2.3} \times {{1}}{{{0}}^{- 5}}$RIU 的折射率范围很宽，从 1.36 到 1.435。数值结果表明，随着相位匹配条件的变化，光纤的结构参数和金层的厚度都会影响传感性能。该工作为OAM-SPR光纤生物传感器的设计提供了理论指导，在传感生物分子和生化液体方面具有巨大的应用潜力。