In order to measure high-precision and large scale sensing signal and solve two-values question in signal detecting of strain sensor, we design a new kind of FBG matching demodulation system based on fiber Bragg grating matching demodulation principle. Through paralleling connection two groups of grating-matching whose center wavelength equal to sensing grating’s, and then analyzing reflectance spectrum, we could get the relationship of strain and optical power detected by photoelectric detector. Then we can set up the theoretical model and complete system simulation. The simulation results show that the scheme is feasible. The scheme not only can solve the problem of double values and can simultaneously detect the positive and negative strain. The sensor measurement range can be up to952ue.
This paper carries out theoretical research and numerical simulation on the temperature characteristics of LPFG magnetic field sensor based on magnetic fluids. The simulation results show that the change of ambient temperature can make coupling resonance wavelength of the long period fiber grating drift, change the refractive index of magnetic fluids, which affects the measurement precision of the magnetic field. Our research has a certain significance for the practical application of LPFG magnetic field sensor based on magnetic fluids.
According to the sensing principle of FBG, the measurement performance of magnetic field sensor based on the differential group delay (DGD) in FBG is discussed in this article. The influence of external environmental parameters, including temperature, stress and pressure, on magnetic field sensor based on DGD are then analyzed from the aspect of theory and simulated through Matlab. As the simulation results indicates, the magnetic field sensing scheme based on DGD is not sensitive to temperature and stress, the specific performance is that the changing temperature or stress can make the DGD spectrum move along the horizontal axis (the wavelength), with the shape unchanged; when temperature variation or phase axial stress maintains the same, the DGD has a linear relation with the magnetic induction intensity. While the external pressure has serious impact on the magnetic field sensing scheme, which is apparently embodied in nonlinear and irregular change of DGD spectrum with the varying pressure.