Compact Mach-Zehnder interferometer based on processed hollow-core fiber for gas pressure sensing

A Mach-Zehnder interferometer based on processed hollow-core fiber (HCF) is proposed and experimentally demonstrated for gas pressure sensing. The fiber sensor is fabricated by splicing a segment of HCF between the two coreless fibers. One end of the HCF is processed into an open cavity, which allows gas pressure of the air-core to be equivalent to that of the external environment. Gas pressure change induces refractive index change of the air-core, thus the measurement of gas pressure can be achieved by monitoring wavelength shift of the interference pattern. The proposed fiber sensor exhibits a high gas pressure sensitivity of 9.35 nm/MPa in the range from 0.1 to 0.04 MPa and a temperature sensitivity of 30 pm/degrees C in the range from 30 degrees C to 90 degrees C. Furthermore, the fiber sensor processes the advantages of compactness, low cost, and all-fiber configuration, which makes it suitable for gas pressure measurement. (C) 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)