| This thesis introduces a novel broad measurement range reflectiveoptical fiber temperature sensing system, on the basis of thetemperature-dependent character of ZnO thin film's optical absorptionspectra and using ZnO thin film deposited on a sapphire triangular prismsurface as sensing material.Zinc oxide is a II-VI group wide band-gap semiconductor sensingmaterial with a high melting point of 1975℃and a high exciton bindingenergy of 60 meV at room temperature (RT). It is receiving much interestin the applications of blue light emitting devices, ultraviolet regionoptoelectronic devices, window materials for display and solar cells andsensing organs such as gas sensing and temperature sensing due to itsgood optoelectronic, piezoelectric properties and high chemical andthermal stability. In this paper, ZnO thin film was first grown on a sapphire prism surface (0001) by electron-beam evaporation (EBE) as atemperature sensing part. AFM and XRD tests showed: it has smoothsurface morphology, good crystallization quality and also strong c-axis(0002) orientation.A novel reflective optical fiber temperature sensor was proposed,based on the aforementioned ZnO thin film as sensing part and in themode of a reflective optical configuration of a triangular prism, afiber-ending located at a convex lens'focus. Spectral transmittancestudies with different temperatures were made for the designedtemperature sensor. It is noticed that the optical absorption edge of ZnOthin film red shifts regularly as temperature increases, and the obtainedband gap energy for ZnO And the thermo-dynamical temperaturecorresponds to a linear formulation of Eg (T) = 3.4205 - 5.2640×10-4×T . Thetheoretical measurement range could be 101800 K. Compared withother traditional temperature sensors, this temperature sensor has asimpler structure, higher stability and broader measurement range, andcan be applied into some extremely environments. |
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