Research On Demodulation Technology Of Short-cavity Interferometric Fiber Fa-Per Pressure Sensor

With the development of industrialization,optical fiber sensing technology has developed rapidly and become a research focus in many fields.Optical fiber Fabry-Perot sensor has many advantages,such as small size,high precision and strong anti-interference,which has been widely used in many fields.In the optical fiber Fabry-Perot sensor system,the demodulation system directly affects the measurement accuracy of the optical fiber Fabry-Perot sensor,so the research on demodulation technology is of great significance.Based on the short cavity interferometric fiber Fabry-Perot pressure sensor,this paper studies the demodulation method and designs a sensor demodulation system based on LabVIEW.The specific content of this article is as follows:A short cavity interferometric fiber Fabry-Perot pressure sensor based on graphene is designed.The mechanical model of graphene pressure sensitive film is established and verified by finite element software.The influence of different layers of graphene film on the center deflection is analyzed.The optical performance of the sensor is simulated by FDTD solutions,and the influence of different Fabry-Perot cavity length on the reflection spectrum is analyzed.As the length of the cavity changes,the reflection spectrum shifts by a certain amount.The shorter the cavity length,the fewer the peaks.The sensor was fabricated by optical fiber etching process,and the pressure measurement system was built.The initial spectral characteristics of the sensor output were analyzed.The Savitzky-Golay filtering method is used to smooth the output spectrum,and the influence of different window widths and different fitting orders on the filtering effect is discussed and analyzed.The result shows that when the window width is set to 151 and the fitting order is 3,the filtering effect is the best.The local fitting method is used to find the location of the trough,and the accuracy of the Gaussian fitting and Lorentz fitting is compared.The results show that the accuracy of Lorentz fitting for finding troughs is better than that of Gaussian fitting for finding troughs.The multi-peak demodulation method is used to demodulate the pressure test data.The results show that the accuracy of this demodulation method is better than the Fourier transform demodulation method for the short cavity interferometric fiber Fabry-Perot pressure sensor,and the sensitivity is 79.95622nm/KPa.According to the modular software design idea,a demodulation analysis system of the dual-channel optical fiber Fabry-Perot sensor is developed based on LabVIEW.The overall framework of the sensor demodulation system is constructed by sub-modules.Completed the interface design of the demodulation system,and based on the designed demodulation algorithm,completed the background program design of the demodulation system,and finally tested and analyzed the demodulation system.