An Optical Fiber Sensor Based on FeOOH Nanorod Arrays for Humidity and Temperature Measurement

It remains a major challenge to prepare a temperature or humidity optical fiber sensor with a simple structure, low cost, and high sensitivity. In this work, a Mach-Zehnder interferometer (MZI) with “SMF-MMF-TCF-MMF-SMF” structure is proposed to measure ambient temperature and humidity. The FeOOH nanorod arrays were grown on the surface of thin core fiber (TCF) to improve the sensitivity of this sensor. This sensor exhibits a high-temperature sensitivity of 859.01 pm/°C in the range of $26~^{\circ }$ C– $52~^{\circ }$ C and a humidity sensitivity of 335.98 pm/% relative humidity (RH) in the range of 40% RH–90% RH. The sensor also exhibits excellent stability and repeatability, with the maximum wavelength deviation caused by temperature change and humidity change being only 0.544 and 0.557 nm, respectively. This sensor is expected to be applied in some fields such as agriculture, chemical industry, and semiconductor manufacturing.