A hydrogen sulfide gas sensor based on a copper/graphene oxide (Cu/GO) coated multi-point thin-core fiber Mach-Zehnder interferometer is proposed and experimentally demonstrated. The single-mode fiber (SMF) is sandwiched between the thin-core-fiber-1 (TCF-1) and thin-core-fiber-2 (TCF-2), and the SMF-TCF-1-SMF-TCF-2-SMF Mach-Zehnder interferometer is obtained. In order to detect the concentration of hydrogen sulfide, Cu/GO composite sensitive film was coated on the outside surface of two thin-core fibers. When the composite film absorbs the gases, it leads to a change of the effective refractive index of the cladding and causes the regular shift of dip wavelength. The result indicates that the thickness of the sensitive film is 1.6 mu m. With the increase of concentration of hydrogen sulfide, the transmission spectra appear blueshift in the range of 0-60 ppm H2S. The linearity of 0.9884 and sensitivity of 4.83 pm/ppm are achieved. In addition, the dynamic response time and recovery time of the hydrogen sulfide sensor are about 32 s and 52 s, respectively. This sensor has the advantages of the small size, simple structure, and easy manufacture, and it is suitable for the detection of trace hydrogen sulfide. (C) 2019 Optical Society of America
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