Chemical Production And Sensing Properties Of Doped Fiber Fabry Perot Sensor

Prof. Rao, the supervisor invented the fabrication method of a fiber-optic Fabrey-Pérot interferometer (FFPI) in fiber by 157nm laser pulses in 2006. In the past few years, the fabrication method, formation mechanism, based characteristics and applications have been extensively investigated. In this thesis, the method of etching the doped fiber and then splicing the etched fiber with the single-mode fiber to form an FFPI is reported. Such a micro Fabry-Perot fiber-optic sensor can be easily fabricated with low cost. The main work is provided as follows:1. In this paper, we reported FFPI fabricated by two steps. Firstly we etched the doped fiber in BHF(HF and NH4F)to form a groove. Secondly we spliced the single -mode fiber with the doped fiber with the groove. It doed not need the expensive laser micro-machining facilities and masks in laser micro-machining. Large quantities of low-cost micrometer FFPI were made easily by control the temperature and time, etc.2. The strain and temperature characteristic experiments of the EFPI fabricated by BHF etching were carried out in the paper. First of all, the author derived the relationship between the FFPI structure and its interference properties in theory. Experimental results show that the sensor has a strain sensitivity of 1.7 pm/μεand a linearity of 0. 9998 within a strain range from 0 to 600με,and a temperature sensitivity of 3.9 pm/μεand a linearity of 0. 9982 within a temperature range from 73℃to 23℃, respectively.3. Two etched Erbium-doped fiber (EDF) are spliced to form the active FFPI. An EFPI sensing system based on optical amplification which can improve the power of the reflective spectrum is designed. This FFPI senor system not only used spontaneous radiation of EDF to form light source but also used EDF to amply the intensity of EFPI sensor signal. A relatively high reflectivity power is achieved while the system cost is not increased.