Study On Sensitive Properties Of Molybdenum Disulfide-nano-coated Fiber Hydrogen Sulfide Gas Sensor

With the development of fiber technology,fiber has been applied in more and more fields such asfibertelecommunication,medical research and sensing technology.Long period fiber gratings?LPFG?is a kind of fiber gratingswith the period from several tens to hundreds of microns,which attracts extensively interestsof many researchers inoptical sensing technology field with its attractive merits.Molybdenum disulfide?MoS₂?,a burgeoninggraphene-likematerial,has distinctive structure and excellent performances,which is widely used in the field of tribology,electrochemical,optical fieldsect.Porous MoS₂ with large specific surface area has remarkable propertiessothat it hasstrong absorption ability,which is available in gas sensor.In this paper,a molybdenum sulfide/citric acid composite membrane-coated long period fiber grating sensor was demonstrated and applied to detect the trace hydrogen sulfide gas.This thesis mainly carried out the following content:?1?The molybdenum sulfide/citric acid composite membrane was prepared by sol-geltechnique.The test of scanning electron micrograph?SEM?shows that the surface of the film has porous structure with large specific surface area.?2?The performance of the gas sensor was tested in the testing platform which was composed of self-designed gas chamber,ASE broadband light source and AQ6370D spectrum analyzer.?3?The sensitive elementwas fabricated by growing molybdenum sulfide/citric acid composite film on the surface of optical fiber grating by using the sol-gel and dip-coating technique.According to the detected results,the sensitivity was 10.52pm/ppm within the concentration range from 0ppm to 70ppm of H₂S.?4?The tapered LPFG pair was fabricated by the fusion welding through using a Furukawa S178A fiber splicing machine.The welding parameters and welding loss was investigated.The tapered LPFG pair is successfully prepared with the transmission losses of 0.03dB in tapered structure.?5?The molybdenum sulfide/citric acid composite film was growing on the surface of the tapered LPFG pair by using the sol-gel and dip-coating technique.Three different films was tested in the experiment and the best sensitivity of the sensor was 8.26 pm/ppm within the concentration range of H₂S.