Study And Application Of Optical Fiber Device And Sensing System Based On Special Fiber Structure

With the active development of optical fiber manufacturing and relative technique,optical fiber sensor has attracted huge attention for its merit.Optical sensor is widely used in the field such as,safety protection,rail transit,construction engineering,pipeline leakage monitor and so on.In this thesis,several kinds of optical fiber interference structures with optical fiber grating are proposed for the measurement of variable parameter including temperature,pressure,refractive index,vibration and position information.The main research achievement as summarized as follows.1.A composite optical fiber structure with mode inference is proposed.The transmisstion characteristic of the sensor is analyzed.The simulation for the transmmistion spectua with different length of no core fiber and single mode fiber in the sensor are carried out.The temperature sensitivity of mode interference and grating repectively is 0.07189 nm/? and 0.01654 nm/?,on the other hand the refractive index sensitivity of mode interference and grating repectively is-111.464 nm/RIU and 0 nm/RIU.According to the theoretical analysis the relitive matrix of wavelength shift and parameter change is obtained through calculating.The vibration sensor is designed and manufactured based on inference structure and fiber grating,and the performance of different sensors is analyzed.The vibration sensor is applied to the train monitoring system,and the information of position and speed is measured in field experiment.2.For the grating stress characteristics an all fiber 2D location sensor based on array of optical fibers is proposed.The central wavelengths of fiber gratings are designed.With the fiber gratings meeting the requirement,the 2D location sensor is achieved.Based on the grating array structure,an all fiber 12-key keyboard is produced.3.A compact sensor for simultaneously measureing temperature and pressure with tube fiber and optical fiber grating is proposed.Based on interference theories,the spectra with different pressure are simulated.The result shows that the pressure sensitivity of the structure is about 2.78 nm/MPa.In the experiment the simultaneous measurement of temperature and pressure is achieved,and the sensitivity of pressure and temperature respectively is 3.9969 nm/MPa and 8.7 pm/?.4.A high sensitivity sensor for temperature or pressure measurement based on tube fiber and refractive index match fluid is proposed.The interference spectra are simulated,and the result shows that the temperature and pressure sensitivity respectively is 5.4 nm/? and-0.0152 nm/Pa.The sensitivity of the free spectrum range is 60.47 nm/MPa.A Fabry Perot interferometer sensor is manufactured and the measurement of temperature and pressure is achieved.The measurement result shows that in a little range of temperature the sensitivity is about 6.96nm/?.In addition the interference spectra with change pressure in a large range are measured,and the sensitivity of the free spectrum range is about 59.9 nm/MPa.