Miniature and high-performance optical fiber relative humidity sensor based on Fabry-Perot structure interacting with hydroxyethyl cellulose.

A miniature Fabry-Perot fiber-optic sensor is demonstrated for high-performance relative humidity (RH) detection. This sensor is constructed by fusing a single-mode fiber to a small section of capillary coating the end with a hydroxyethyl cellulose film (HEC). The effects of capillary length and hydroxyethyl cellulose concentration on the RH response are investigated to obtain the preferential condition with capillary length of 102 μm and HEC concentration of 0.03 g/ml. A testing RH sensitivity of 1.24 nm/%RH can be achieved in the range of 48%RH to 60%RH. Simultaneously, small hysteresis errors are demonstrated in the tests with increasing and decreasing RH values. The dynamic measurements reveal a response time of 1.61 s and a recovery time of 2.1 s. The high sensitivity, good stability and simple fabrication process of the sensor make it promising for practical applications of relative humidity sensors. • RH sensor includes Fabry-Perot interferometer and capillary coated hydroxyethyl cellulose film. • The sensor has a fast response with a response time of 1.61 s and a recovery time of 2.1 s. • The sensor achieves a RH sensitivity of 1.24 nm/%RH in the range of 48%RH to 60%RH. • The sensor has high sensitivity, low hysteresis error, and good stability. [ABSTRACT FROM AUTHOR]