Study On Miniature Fiber-Optic Pressure Sensor Based On Silver Film

Based on multiple-beam interference principle of F-P interferometer cavity, optical fiber Fabry-Perot (F-P) sensor is used to accurately measure many physical quantities. In this paper, by silver mirror reaction, we have demonstrated the preparation of a kind of nano-silver film with thickness of 130nm and reflectivity of 95% in 1550nm wavelength. Based on the silver film mentioned above, we designed an extrinsic F-P interferometer (EFPI) showing a high contrast. After that, we analyzed the impact of cavity length change on interference free spectral range and light intensity output. Meanwhile, by a series of optimization operation, we determined the interference cavity length and the light wavelength of working point and established a set of stable fiber F-P pressure sensor system. The results show that the simple and intensive sensing system displays high sensitivity for detecting pressure up to 0.29μw/KPa and good linearity of response to pressure with minimum pressure resolution of 0.5KPa.The structure of the paper is as follows:ChapterⅠ, the characteristics of optical fiber F-P sensor is introduced and then the fabrication and research status of optical fiber F-P sensor in the field of industrial and biomedical is demonstrated. Finally, the main contents of this paper are summarized and innovation illustrated.ChapterⅡ, firstly, the principle of F-P cavity Interferometer is introduced, and then two main types of optical fiber F-P sensor including IFPI and EFPI are summed up. Hereafter, we analyzed two methods of signal demodulation, including the wavelength demodulation and the intensity demodulation.ChapterⅢ, by retrieving the development of miniature EFPI pressure sensor technology reported at home and abroad, production methods and materials selected of the diaphragm are analyzed. By silver mirror reaction, we produce a high-reflectivity silver film with thickness of 130nm. Meanwhile, we analyzed the factors that affect the production of diaphragm by experiment. Based on the analysis of diaphragm and the loss of F-P cavity, by micro-regulation change of the cavity length, we have produced a fiber-optic F-P pressure sensor with high contrast up to 21dB.ChapterⅣdesigns a pressure calibration experiment. The results show this sensor has higher sensitivity for detecting pressure and reaches to 0.29μw/KPa and pressure minimum resolution of 0.5KPa.The sensitivity of demodulation wavelength reaches to 77.88nm/KPa. The structure is simple, small, real time, linearity of response to pressure has reasonable.Chapter V reviews of the full paper. And then, according to research reported in this paper, some ideas of the future research work is offered.