Analysis of the Characteristics of PVA-Coated LPG-Based Sensors to Coating Thickness and Changes in the External Refractive Index
Analysis of the Characteristics of PVA-Coated LPG-Based Sensors to Coating Thickness and Changes in the External Refractive Index
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DOI：
10.1109/jsen.2012.2230534
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发表时间：
2013-03-01
影响因子：
4.3
通讯作者：
Grattan, Kenneth T. V.
中科院分区：
文献类型：
--
作者：
Alwis, Lourdes;Bremer, Kort;Grattan, Kenneth T. V.
最近的研究表明，写入光纤的长周期光栅（LPG）的透射光谱对沉积在其上的薄层的厚度和折射率（RI）敏感，这一概念形成了许多光纤传感器的基础。本文报道的研究特别集中在这种类型的传感器上，以创建具有在LPG上形成高灵敏度探针的基础的聚乙烯醇（PVA）的沉积层的优化厚度的设计。在创建这样的传感器，浸涂技术被用来最大限度地减少由涂层表面的不均匀性导致的衰减带中的有害影响。在本文中，具有不同涂层厚度的LPG均匀地涂覆有PVA薄层，并浸没在已知RI在1.30至1.70的范围内的油中，以创建有效的RI探针。观察到，当涂层厚度达到使得覆盖层内的光功率能够基本上重新分布的特定值时，即使当覆盖层具有比包层的RI高的RI时，也可以实现传感器的最大灵敏度。通过表征所开发的设备所获得的实验结果被证明是在良好的协议与理论模型的结果。
Recent research has shown that the transmission spectrum of a long period grating (LPG) written into an optical fiber is sensitive to the thickness and the refractive index (RI) of a thin layer deposited on it, a concept which forms the basis of a number of optical fiber sensors. The research reported herein is focused, in particular, on sensors of this type to create a design with an optimized thickness of the deposited layers of polyvinyl alcohol (PVA) on LPGs forming the basis of a highly sensitive probe. In creating such sensors, the dip-coating technique is used to minimize deleterious effects in the attenuation bands resulting from the inhomogeneity of the coated surface. In this paper, LPGs with different coating thicknesses are uniformly coated with thin layers of PVA and submerged in oils of known RI over the range from 1.30 to 1.70, to create effective RI probes. It is observed that when the coating thickness reaches a particular value that enables a substantial redistribution of the optical power within the overlay, a maximum sensitivity of the sensor can be achieved, even when the overlay has a RI higher than that of the cladding. The experimental results obtained through the characterization of the devices developed are shown to be in good agreement with the results of a theoretical model.