Design And Research Of Optical Fiber F-P Pressure Sensor Based On Microcavity Structure

In recent years,fiber optic pressure sensors have gained more and more in-depth research in various scientific research institutions due to its small size,high sensitivity and easy integration,which are widely used in pressure sensing in harsh environments such as oilfield logging.In addition to the advantages of the traditional fiber-optic sensor,the fiber-optic F-P pressure sensor based on the Fabry-Perot Interference(FPI)structure has the advantages of high measurement accuracy and low cross-sensitivity,so it can be used for single measurement of external physical parameters such as temperature,strain and pressure to meet the needs of practical sensing applications.Since the structural characteristics of F-P interferometer have obvious influence on the measurement properties of fiber optic F-P sensor,The fiber optic F-P pressure sensor based on microcavity structure is taken as the research target in this paper.This paper mainly accomplishes the following work: Proposing fiber-glass tube-fiber microcavity structure and testing its pressure sensing characteristics.The egg-shaped microbubble structure was selected as subsequent research object,and the three-dimensional precision platform was built to study the egg-shaped microbubble-fiber structure.The interference cavity length information was demodulated by Fourier Transform White Light Interferometry(FTWLI).This sensing structure is finally packaged and tested for the single pressure sensitivity.The experimental result shows that the fiber-glass tube-fiber structure proposed in this paper is suitable for pressure sensing in high pressure environment and has sensitivity of 4.7 pm/kPa.The pressure sensitivity of the proposed egg-shaped microbubble-fiber structure is 11.1 pm/kPa,and the maximum deformation sensitivity of its F-P interference cavity length to pressure is 0.334 nm/kPa.The packaged structure has a pressure sensitivity of 8.6 pm/kPa and good temperature resistance and enables remote measurement of pressure.The microcavity sensing structure studied in this paper can be applied to the actual pressure sensing,which can provide an effective reference for the fiber optic F-P pressure sensor with low cost,high sensitivity and strong temperature interference resistance.