Optical fiber Fabry-Perot sensor based on BPQDs-PVA compound for humidity measurement

A high-sensitivity fiber humidity sensor based on Fabry-Perot interferometer is experimentally proposed. The sensor is fabricated by coating black phosphorus quantum dots (BPQDs)-polyvinyl alcohol (PVA) film on the end face of single mode fiber via controllable dipping method. Benefit from the BPQDs-PVA based cavity, the length and the refractive index of the BPQDs-PVA compound changes with ambient humidity, evidently modulating the interference spectrum. Experimental results show that the sensor achieves a maximum humidity sensitivity of 4.844 nm/%RH in the humidity range of 33%-56%RH with a low temperature cross sensitivity of 0.017%RH degrees C-1. Meanwhile, stability test exhibits a low instability of 0.016%RH. Together with the advantages of simple manufacture, small size and fast response, the sensor has broad practical application prospect.