Sensitivity improved tapered optical fiber sensor for dissolved oxygen detection

• Published in: Instrumentation science & technology 2021-01, Vol.49 (1), p.32-44
• Main Authors: Wu, Zhuo-Hui, Wang, Qi, Duan, Jia-Xing, Sun, Hong-Zhi, Zhao, Qiang
• Format: Article
• Language: English
• Subjects: Beams (radiation); Dissolved oxygen; finite difference beam propagation method; Finite difference method; Fluorescent dyes; Fluorescent indicators; layer-by-layer self-assembly; optical fiber sensor; Optical fibers; Oxygen; Oxygen probes; Response time; Self-assembly; Sensitivity; Sensors; Surface stability; tapered optical fiber; Temperature
• ISSN: 1073-9149; 1525-6030
• DOI: 10.1080/10739149.2020.1774776

A new method to improve the sensitivity of a fiber-based dissolved oxygen sensor by enhancing the evanescent field on the surface of optic fiber has been proposed and verified. The finite difference beam propagation method was used to simulate the transmission of light into the fiber. According to the simulation results, the evanescent field intensities of the step type fiber and tapered fiber were analyzed. Subsequently, a tapered fiber and step type fiber were fabricated. The layer-by-layer self-assembly process was used to place the fluorescent dye onto the surface of fiber. The reversibility, stability, response time, and temperature characteristics of the tapered fiber sensor were characterized. The experimental results show that the sensor has good repeatability, stability and temperature stability, with a response time of approximately 88 s for a change in dissolved oxygen concentration from 0 to 15 mg/L. The experimental measurements showed that the sensitivity of the tapered fiber dissolved oxygen sensor is 1.3-fold higher for dissolved oxygen concentrations from 0 to 15 mg/L compared to the step type fiber device.