Theoretical modeling and investigations of AZO coated LMR based fiber optic tapered tip sensor utilizing an additional TiO2 layer for sensitivity enhancement
Theoretical modeling and investigations of AZO coated LMR based fiber optic tapered tip sensor utilizing an additional TiO2 layer for sensitivity enhancement
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DOI：
10.1016/j.snb.2016.07.032
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发表时间：
2017
影响因子：
8.4
通讯作者：
N. Paliwal;J. John
中科院分区：
文献类型：
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作者：
N. Paliwal;J. John
提出了铝掺杂氧化锌(AZO)和二氧化钛(Ti02)涂层的有损模式谐振(LMR)光纤锥形针尖传感器的理论模型。在基于LMR的FO锥形针尖传感器中，传感信号是用回反射光谱来测量的，而传统的LMR传感器是用透过率来测量的。所提出的传感器的一个主要优点是需要较小的样本量。此外，其紧凑的锥形尖端设计使其更适合于点传感。在这项工作中，首次对AZO涂覆LMR基FO锥形针尖传感器进行了详细的分析。此外，还研究了AZO和TiO2厚度比以及光纤尖端半径、尖端长度和数值孔径等参数对反射光谱的影响。与传统的锥形LMR传感器相比，提出的几何结构加上各种光纤参数和薄膜厚度比的适当组合，使传感器的灵敏度提高了近六倍。并将该传感器的灵敏度与普通光纤的灵敏度进行了比较。该传感器的折射率(RI)灵敏度在1500-9000 nm/RIU范围内。
This article presents a theoretical model for lossy mode resonance (LMR) based fiber optic (FO) tapered tip sensor coated with aluminum doped zinc oxide (AZO) and titanium dioxide (TiO2) layer. In LMR based FO tapered tip sensor, sensing signal is measured in terms of retro-reflecting spectra whereas in conventional LMR sensors it is measured in terms of the transmittance. A major advantage of the proposed sensor is that it requires small sample volume. Also its compact tapered tip design makes it more suitable for point sensing. In this work, for the first time, a detailed analysis of AZO coated LMR based FO tapered tip sensor has been carried out. Additionally, the combined effect of AZO and TiO2thickness ratio along with the fiber parameters such as fiber tip radius, tip length and numerical aperture on the reflectance spectrum has been investigated. The proposed geometry along with appropriate combination of various fiber parameters and the thin films thickness ratio provides approximately sixfold increase in the sensitivity compared to the conventional tapered LMR sensors. Sensitivity of the proposed sensor has also been compared with straight fiber geometry. Refractive index (RI) sensitivity of the proposed sensor is in the range of 1500–9000 nm/RIU.