Research On Pressure Sensor Based On Sagnac And F-P Sensitization Technology

Optical fiber sensors are widely used in pressure measurement due to their small size,immunity to electromagnetic interference,and strong environmental adaptability.Based on the Vernier effect and the Sagnac interference characteristics of polarization-maintaining photonic crystal fibers,a separate pressure sensing structure using F-P cavity sensitization is proposed,and the traditional Sagnac interference ring is improved into a linear type,so that the sensor has a simpler structure.The sensing system is an all-fiber structure and has the potential to work in a high-pressure environment.The main content of the paper is as follows:Firstly,the advantages and disadvantages of several optical fiber pressure sensors are compared.The advantage of Sagnac interferometric pressure sensor in pressure sensing is analyzed,the research status of optical fiber pressure sensors is described,and the principle of Fabry-Perot interference,polarized light interference,and vernier effect are analyzed.The photonic crystal fiber analysis method is introduced in detail,which provides a theoretical basis for the follow-up simulation and experimental research of this article;Secondly,the pressure sensitivity theory of polarization-maintaining fiber is studied,the pressure-birefringence sensitivity of Panda polarization-maintaining fiber,polarizationmaintaining photonic crystal fiber and side-hole fiber is analyzed by finite element method.Comprehensive comparison,choose the polarization-maintaining photonic crystal fiber as the sensing fiber of the pressure sensing system;Thirdly,the interference principle of a single linear Sagnac sensor is studied,the basic interference characteristics of linear Sagnac are explored from both simulation and experiment.A single linear Sagnac pressure sensing system was built,the pressure sensitivity of the sensor composed of 40.2cm polarization-maintaining photonic crystal fiber reaches 5.3nm/MPa,and has good linear characteristics.Through experiments,the temperature sensitivity of the sensor is-0.0291nm/?,which is two orders of magnitude smaller than the pressure sensitivity;Finally,the basic principles of pressure sensors based on linear Sagnac and F-P sensitization structure are studied.Through simulation,the system's sensitivity enhancement mechanism and the corresponding pressure sensitivity magnification under different F-P cavity lengths are explored.An experimental system was built,and it was confirmed through experiments that the structure does increase the sensitivity.Three sets of F-P cavities with different cavity lengths were made for pressure sensitization experiments,which proved that changing the F-P cavity length can change the sensitization multiple and increase the pressure sensitivity to 35.09nm/MPa.