Spatially Modulated Fiber Speckle for High-Sensitivity Refractive Index Sensing

Autor: Penglai Guo, Huanhuan Liu, Zhitai Zhou, Jie Hu, Yuntian Wang, Xiaoling Peng, Xun Yuan, Yiqing Shu, Yingfang Zhang, Hong Dang, Guizhen Xu, Aoyan Zhang, Chenlong Xue, Jiaqi Hu, Liyang Shao, Jinna Chen, Jianqing Li, Perry Ping Shum
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Sensors, Vol 23, Iss 15, p 6814 (2023)
Druh dokumentu: article
ISSN: 1424-8220
DOI: 10.3390/s23156814
Popis: 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−1 compared to the one without offset. The developed TMMF speckle sensor shows an RI resolution of 5.84 × 10−5 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.
Databáze: Directory of Open Access Journals
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