Guo Penglai, Liu Huanhuan, Zhou Zhitai, Hu Jie, Wang Yuntian, Peng Xiaoling, Yuan Xun, Shu Yiqing, Zhang Yingfang, Dang Hong, Xu Guizhen, Zhang Aoyan, Xue Chenlong, Hu Jiaqi, Shao Liyang, Chen Jinna, Li Jianqing, Shum Perry Ping
School of Computer Science and Engineering, Faculty of Innovation Engineering, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau 999078, China.
Department of Electronic and Electrical Engineering, College of Engineering, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen 518055, China.
Sensors (Basel). 2023 Jul 31;23(15):6814. doi: 10.3390/s23156814.
A fiber speckle sensor (FSS) based on a tapered multimode fiber (TMMF) has been developed to measure liquid analyte refractive index (RI) in this work. By the lateral and axial offset of input light into TMMF, several high-order modes are excited in TMMF, and the speckle pattern is spatially modulated, which affects an asymmetrical speckle pattern with a random intensity distribution at the output of TMMF. When the TMMF is immersed in the liquid analyte with RI variation, it influences the guided modes, as well as the mode interference, in TMMF. A digital image correlations method with zero-mean normalized cross-correlation coefficient is explored to digitize the speckle image differences, analyzing the RI variation. It is found that the lateral- and axial-offsets-induced speckle sensor can enhance the RI sensitivity from 6.41 to 19.52 RIU compared to the one without offset. The developed TMMF speckle sensor shows an RI resolution of 5.84 × 10 over a linear response range of 1.3164 to 1.3588 at 1550 nm. The experimental results indicate the FSS provides a simple, efficient, and economic approach to RI sensing, which exhibits an enormous potential in the image-based ocean-sensing application.
在本研究中，已开发出一种基于锥形多模光纤（TMMF）的光纤散斑传感器（FSS）来测量液体分析物的折射率（RI）。通过将输入光横向和轴向偏移进入TMMF，在TMMF中激发了几个高阶模，散斑图案在空间上被调制，这会在TMMF输出端产生具有随机强度分布的不对称散斑图案。当TMMF浸入折射率发生变化的液体分析物中时，它会影响TMMF中的导模以及模式干涉。探索了一种采用零均值归一化互相关系数的数字图像相关方法来数字化散斑图像差异，分析折射率变化。研究发现，与无偏移的散斑传感器相比，横向和轴向偏移引起的散斑传感器可将折射率灵敏度从6.41提高到19.52 RIU。所开发的TMMF散斑传感器在1550 nm波长下，在1.3164至1.3588的线性响应范围内，折射率分辨率为5.84×10。实验结果表明，该光纤散斑传感器为折射率传感提供了一种简单、高效且经济的方法，在基于图像的海洋传感应用中具有巨大潜力。
