Research On Preparation And Properties Of Optical-fiber Hydrogen Sensor Structure

In recent years, with the application of hydrogen enlarging constantly, thedetection of hydrogen concentration is becoming more and more important. Becauseof the particular advantages of optical fiber type hydrogen sensor, it has becomehotspot contents of research. The research of optical fiber type hydrogen involvesnot only optical waveguide transmission theory of optics, but also preparation ofhydrogen sensitive film in chemical material field. Now the types of optical fiberhydrogen sensors are various, and the response to hydrogen is much more ideal. Butthere are still many problems, such as bad stability and repeatability and so on, sothere is a long way to go to commercialize the optical fiber hydrogen sensor. Thus,so far, making out long-life and low-cost optical fiber hydrogen with highsensitivity is facing huge challenge.The research of this paper focuses on D-shaped optical fiber hydrogen sensorof elapse field and single mode-multimode-single mode (SMS) optical fiberhydrogen sensor after comparing merits and demerits of various kinds of opticalfiber hydrogen sensors.In this paper kinds of hydrogen sensitive film, properties of palladiummembrane and methods to make palladium membrane were introduced. Weprepared palladium membrane using the method of electroless plating, and gotpalladium membrane under different temperature after determining the compositionratio of plating solution. The test results show that the effect of coating film is bestwhen the temperature is60, and the film made using the method of electrolessplating is not only uniform, but also strongly adhesion to optical fiber. Besides that,the experiment is easy to carry out with low cost. To D-shaped optical fiberhydrogen sensor, we firstly analyzed light transmission theory in optical fiber,simulated its transmission depth using Beamprop. Through experiments, it turns outthat the light transferred in optical fiber is most sensitive to outside environmentwhen the energy drops down to80%of initial value. The regular pattern of thecorrosion depth, time and optical power variation was obtained. D-shaped opticalfiber was made by femtosecond laser. After further etched, it was coated with Pdmembrane. The performance of the D-shaped fiber optic hydrogen sensor based on single-mode was tested. To SMS structure fiber optic hydrogen sensor, we analyzedthe sensor theory and made SMS optical fiber with a certain length multimode fiber.We obtained the change rules of output light power with corrosion time. Theperformance of SMS structure fiber optic hydrogen sensor was tested by opticalspectrum instrument and optical power meter.In this paper we designed a set of unique optical fiber corrosion in-line-testsystem and hydrogen concentration test system. At last we analyzed the result of theexperiment. Both the theory and experiments show that the potential applicationvalue of optical fiber hydrogen sensor is huge.