Compact high-sensitive Mach-Zehnder-based optical fiber sensor for monitoring gaseous acetone concentrations

A high-sensitivity, fine selectivity, and good repeatability optical fiber sensor has been proposed and fabricated for trace detection of acetone vapor concentration in the environment based on the Mach-Zehnder interferometer. The proposed sensor construction was made by splicing a no-core fiber (NCF) segment between two single-mode fiber (SMF) segments to form SMS construction. The specific interaction of acetone with the sensitive taper region of the NCF varied the effective refractive index of the propagating modes, permitting the determination of acetone concentration via tracking the interference fringes of the transmitting spectra. The resultant data show that the fabricated fiber sensor can realize the highest sensitivity with about 1.287$\times {10}^{-5}$ nm/ppm with a detection limit of 38 ppm in the 3.5 $\times {10}^5$–9.5$\times {10}^5$ ppm concentration range. This sensor shows high stability with good repeatability and a fast response time. Meanwhile, the proposed sensor has a high ability in biomedical applications for early diagnosis of diseases and examination, as it can identify and detect lots of biological elements by employing the correlation between physical parameters and the resultant alteration in interfering fringes.