Influence of Sensor Dimensions and Ambient Humidity on the Performance of ReS2-Coated Fiber Optic Humidity Sensors

Abstract

Optical sensors offer appealing features such as being compact and lightweight, electrically passive operation, and electromagnetic-field immunity, making them a promising tool for achieving high sensitivity and fast response in compact platforms, despite significant progress in humidity sensing. The integration of functional materials with optical fiber platforms has opened new avenues for enhancing humidity sensing performance. Therefore, in this study, the fiber-optic humidity sensors have been improved by adding a rhenium disulfide (ReS2) coating, which leverages the material’s unique electronic and optical properties as a two-dimensional compound. Several tapered optical fibers with diameters of 4 μm, 7 μm, and 10 μm were fabricated using the pull-heat method to study the effect of diameter on sensing performance. The sensors were then tested within a humidity range of 40% to 80% to evaluate their sensitivity and linearity, using a laser source and the Optical Spectrum Analyzer. The experimental result reveals that ReS2-coated tapered fibers consistently outperform uncoated fibers in terms of sensitivity, where the fiber coated with a 10μm ReS2 layer exhibited the most significant enhancement, achieving an increase of approximately 6-8% across the tested humidity range. The study also showed that incorporating the ReS2 coating onto the fiber leads to a clear improvement in the performance of fiber-optic sensors for environmental humidity monitoring.