Wang Xueping, Zhao Chun-Liu, Li Jihui, Jin Yongxing, Jin Shangzhong
Institute of Optoelectronic Technology, China Jiliang University, Hangzhou 310018, People's Republic of China.
Rev Sci Instrum. 2013 Apr;84(4):043114. doi: 10.1063/1.4803005.
A simple multipoint humidity measurement by polyvinyl alcohol (PVA)-coated Fresnel reflection-based optical fiber sensors with an Array-Waveguide Grating (AWG) is proposed and demonstrated. Every channel end of the AWG is split as a vertical planar surface, and then is coated with a layer of a PVA whose refractive index is sensitive to moisture. The reflection intensity for each channel will change with its surrounding humidity, since the optical fiber interface's Fresnel reflection is affected strongly by the refractive index difference of the interface two sides. Multiplexing is achieved by the AWG with 16 channels, in which 15 channels can be used as sensing heads when they are coated with a layer of PVA and the left one is used as a reference channel. The experimental setup is simple and easy to handle. Experimental results show that the proposed Fresnel reflection-based optical fiber sensor for multipoint humidity measurement works well and the average sensitivity is 0.135 dB∕% relative humidity (RH) within the measurement range of 30%-80% RH.
提出并演示了一种基于聚乙烯醇（PVA）涂层的菲涅尔反射型光纤传感器与阵列波导光栅（AWG）相结合的简单多点湿度测量方法。AWG的每个通道末端都被分割成一个垂直平面，然后涂覆一层对湿度敏感的PVA。由于光纤界面的菲涅尔反射受界面两侧折射率差的强烈影响，每个通道的反射强度会随其周围湿度而变化。通过具有16个通道的AWG实现复用，其中15个通道在涂覆一层PVA后可作为传感头，剩下的一个用作参考通道。实验装置简单且易于操作。实验结果表明，所提出的基于菲涅尔反射的光纤多点湿度传感器工作良好，在30% - 80%相对湿度（RH）的测量范围内，平均灵敏度为0.135 dB∕%相对湿度（RH）。
