Simultaneous measurement of trace organic vapors and temperature by use of zeolite thin film-coated fiber spherical end face and fiber Bragg grating

摘要

An optical fiber spherical end face coated with zeolite thin film is used together with a fiber Bragg grating (FBG) for simultaneous measurement of trace organic vapor and temperature. The fiber spherical end face is fabricated by using electrical arc discharge on single mode fiber and then coated with zeolite thin film. The FBG is placed in front of the zeolite film-coated fiber spherical end head. The coated fiber spherical end essentially forms an intrinsic Fabry-Perot (F-P) cavity. The trace chemical vapor concentration is measured by monitoring the interference wavelength shift of the coated optical fiber spherical F-P sensor head, due to the zeolite film adsorption to organic vapor molecules. Meanwhile, temperature is measured by monitoring the Bragg wavelength shift of the FBG. The experimental results show that the proposed trace organic vapor sensor exhib-its a high sensitivity, which is 1.199 nm/ppm for isopropanol within the range from 0 to 20 ppm, and the temper-ature sensitivity is 10.2 pm/℃ within the range from 30°C to 70°C. Such a sensor has high sensitivity, excellent repeatability, fast response, and real-time monitoring capability.