Low Crosstalk Dual Parameter Fiber Optic Sensor for Simultaneous Temperature and pH Detection Based on Femtosecond Laser Processing
Pengqi Gong, Xuegang Li, Xue Zhou, Fang Wang, Yanan Zhang, Yong Zhao
Abstract
This study presents a groundbreaking dual-channel sensing technology embedded within a meticulously fabricated microcavity optical fiber structure using femtosecond laser technology. This microcavity design enables the generation of both surface plasmon resonance (SPR) and Mach-Zehnder interferometer (MZI) signals, eliminating crosstalk—a critical challenge in traditional multi-parameter sensing. This achievement ensures a precise one-to-one correspondence between output signals and the measured variables. Using layer-by-layer self-assembly, the SPR sensing region was selectively modified with a pH-sensitive material. In parallel, the temperature-sensitive material was integrated into the microcavity via microfluidic filling. This dual approach facilitates the simultaneous detection of temperature and pH levels. Experimental results validate the technology's exceptional capabilities: the SPR channel exhibits a remarkable sensitivity of −16.5 nm/pH for pH monitoring, while the MZI channel demonstrates a sensitivity of 1.15 nm/ °C for temperature detection. These values represent significant advancements over previous studies. The sensor developed in this research offers several key advantages: simultaneous temperature and pH measurement, minimized crosstalk, and outstanding sensitivity. This technology holds tremendous promise for enhancing water quality monitoring, safeguarding aquatic environments, and controlling water pollution, marking a significant step forward in environmental protection technologies.