PMMA-coated SMF-CLF-SMF-cascaded fiber structure and its humidity sensing characteristics

An optical fiber humidity sensor based on the extrinsic Fabry-Perot interference (EFPI) structure has been proposed. Polymethyl methacrylate (PMMA) film was inserted as the humidity sensing actuator between a coreless fiber (CLF) and the single mode fiber (SMF). The relative humidity (RH) sensing performance has been experimentally demonstrated with the sensitivity of 0.1747 nm/%RH and response time of 4.5 min in the range of 25-80%RH. The temperature depend-free property has been verified during 30-55 degrees C, revealing its good stability in the practical environment. Due to the compact structure, miniature scale, the proposed fiber probe can be integrated with the common SMF system to determine the environmental humidity in the way of the remote and distributed network.

Automated summary

An optical fiber humidity sensor based on the extrinsic Fabry-Perot interference structure is proposed in this paper. The sensor demonstrates high sensitivity and fast response time, with temperature independence within a certain range, making it suitable for practical applications. The compact size and integration capability of the fiber probe with the common single mode fiber system enable remote and distributed humidity measurement in a network.