Research On High Precision Fiber Bragg Grating Demodulation System Based On Tunable Scanning Laser

With the development of optical fiber sensing technology,more and more optical fiber sensors and their demodulation equipment have been developed in succession.However,the demodulation precision,resolution,and bandwidth of existing demodulation products cannot meet the requirements of high-precision detection.Therefore,the research of high-precision,high-reliability fiber-optic sensing devices is of great significance.Based on the application of fiber Bragg gratings,this paper compares the advantages and disadvantages of the existing demodulation methods with respect to the development status of fiber Bragg grating demodulation systems at home and abroad.A high-precision FBG sensor demodulation system is proposed based on a tunable scanning laser for high-precision FBG demodulation system.The main research contents include: the demodulation system optical path design,tunable scanning laser hardware design,F-P filter and other key device development,demodulation system software implementation and wavelength extraction optimization algorithm research.Firstly,according to the advantages and disadvantages of the existing fiber grating demodulator,a tunable scanning laser demodulation method is proposed.The key device F-P filter of the system was prepared to suitable for this system,F-P filter free spectral range up to 50 nm,and with the fineness of 1000.In addition,the performance of other optical devices was analyzed,and the overall optical path design of the demodulation system was completed.Secondly,the design of the laser hardware circuit is completed,including the design and analysis of the pump driver circuit,the design and implementation of the temperature control circuit,the design of the amplifier circuit,and the application of the photoelectric conversion technology.At the same time,based on the hardware system,a set of demodulation system software based on LabVIEW was developed.The real-time demodulation and real-time storage functions of the demodulation system are realized.Finally,aiming at the difficulty of high-precision demodulation test calibration,this paper proposes a method using the etalon as the measured object to complete the system calibration.The demodulation precision and wavelength distribution relationship at different scanning frequencies are analyzed.Based on the distribution of demodulated data,a wavelength optimization algorithm is proposed to further improve the demodulation precision.Finally,a high precision fiber grating demodulation system with a demodulation precision of 0.8pm,a demodulation bandwidth of 1525-1565 nm,and a stability of 0.8pm was developed.