High-sensitivity optical fiber relative humidity probe with temperature calibration ability.

Abstract

A high-sensitivity optical fiber relative humidity (RH) sensing probe with the ability of temperature calibration is proposed and experimentally demonstrated. It consists of a simple Fabry-Perot interferometer constructed by coating a layer of thin polyimide (PI) film on the end face of single-mode fiber and an upstream fiber Bragg grating (FBG). PI is one of the organic polymer humidity-sensitive materials with good comprehensive properties. The cascaded FBG is used for temperature calibration and elimination of the temperature cross-sensitivity in the process of measuring RH. Experimental results show that this sensing probe can realize simultaneous measurement of temperature and RH. The RH response sensitivity reaches up to 986.25pm/%RH. This sensing probe with the advantages of simple structure, compact size, high sensitivity, easy packaging, and dual-parameter measurement has an extensive application prospect.