Effect of MoS2 coated on tapered optical fiber for humidity sensor

Abstract

This study investigates the influence of tapered optical fiber diameter and MoS₂ concentration on the sensitivity of optical humidity sensors fabricated using the heat-and-pull method. Optical fibers with tapered diameters of 3 µm, 5 µm, and 7 µm were analyzed under varying humidity levels (40%, 50%, and 60%). Additionally, the effect of different MoS₂ concentrations 2 µl, and 4 µl coated on the fiber surface was examined for each diameter. Experimental results demonstrate that smaller fiber diameters yield significantly higher sensitivity, with the 3 µm fiber showing the greatest power response at all humidity levels-up to 35.07% more sensitivity at 40% humidity compared to 7 µm fibers. Furthermore, increasing MoS₂ concentration enhances the sensor response across all diameters, with the 4 µl concentration consistently delivering the highest power output. For example, at 40% humidity, a 4 µL concentration on a 7 µm fiber produced an 18.89% increase in sensitivity compared to an uncoated fiber. These findings highlight that both reduced fiber diameter and increased MoS₂ concentration significantly improve the sensitivity of optical humidity sensors, offering a promising approach for developing high-performance environmental sensing devices.