Optical Fiber Fabry-Perot Humidity Sensor Based on BPQDs-PVA Sandwiched in SMF

An optical fiber humidity sensor based on filmy black phosphorus quantum dots- polyvinyl alcohol (BPQDs-PVA) gel sandwiched between two sections of single-mode fibers (SMFs) is proposed. The BPQDs-PVA compound serves as Fabry-Perot (FP) cavity that directly perceives external humidity variations and modulates the reflection spectrum. Based on the excellent hygroscopicity of BPQDs-PVA compound, the humidity sensor achieved a humidity sensitivity of 0.2259 nm/%RH in the range of 42–57 %RH, and an ultra-high humidity sensitivity of 12.4307 nm/%RH in the range of 57–60 %RH. The maximum instability of the sensor is 0.02 %RH, and the response/recovery time are 0.78s/1.24s, respectively. Easy fabrication process, low cost, good stability and high sensitivity make it has great potential in fields which need accurate humidity monitor and control.