Owing to their high sensitivity, surface plasmon resonance (SPR)-based sensors depict broad application prospects in biochemical detection, environmental monitoring, and food safety. In this paper, an optical fiber-based SPR sensor is proposed and demonstrated for the refractive index (RI) detection of liquid samples. This sensor is composed of a multimode fiber (MMF), a no-core fiber (NCF), and another MMF that is connected in sequence. The length of the NCF is 2 cm. A thin silver film is deposited on the NCF surface to stimulate the SPR effect. Experimental results indicated that the shift amount of resonance dip wavelength is as high as 303.6 nm as RI increases from 1.333 to 1.4107. A sensitivity of 2507.58 nm/RIU with a fitting linearity ${R^2}$ of 0.9931 is obtained in the lower RI region of 1.333–1.3723, while the sensitivity and ${R^2}$ reaches 5228.21 nm/RIU and 0.97395, respectively, in the higher RI region of 1.3723–1.4107. Compared with previously reported RI sensors, the proposed fiber optic SPR sensor exhibits the advantages of simple structure, small volume, low cost, high sensitivity, and wide detection range.

中文翻译：

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基于涂有银膜的无芯光纤的高性能表面等离子体共振折光仪

由于其高灵敏度，基于表面等离子体共振（SPR）的传感器在生化检测、环境监测和食品安全方面具有广阔的应用前景。在本文中，提出并演示了一种基于光纤的 SPR 传感器，用于液体样品的折射率 (RI) 检测。该传感器由多模光纤 (MMF)、无芯光纤 (NCF) 和另一个依次连接的 MMF 组成。NCF 的长度为 2 厘米。在 NCF 表面沉积一层薄银膜以刺激 SPR 效应。实验结果表明，随着RI从1.333增加到1.4107，共振倾角的偏移量高达303.6 nm。灵敏度为 2507.58 nm/RIU，具有拟合线性${R^2}$在较低的 RI 区域 1.333–1.3723 中获得 0.9931，而灵敏度和${R^2}$在较高的 RI 区域 1.3723–1.4107 中分别达到 5228.21 nm/RIU 和 0.97395。与之前报道的 RI 传感器相比，所提出的光纤 SPR 传感器具有结构简单、体积小、成本低、灵敏度高和检测范围广的优点。