Based On The Interference Structure Of The Magneto-optical Fiber Bragg Grating

In recent years, with rapid development of optical fiber technology and fiber communication, Fiber Bragg Gratings (FBGs) have already become one of the fastest developing optical passive components, and play an important role in the field of fiber sensing. Magneto-optical fiber Bragg grating (MFBG), as a novel multifunctional grating, has drawn more attention because of its unique characteristics. The combination of interferometers and FBGs are often used for signal demodulation, sensing and detection in many fields, such as medical, industrial, aerospace, bridge,etc.The paper discusses the MFBG-based interferometers as follows:1. According to the symmetry of transmission matrix for non-uniform magneto-optic fiber Bragg gratings (MFBGs), the Optisystem simulation model of the non-uniform MFBG has been built up. The simulation model is veridied by the MATLAB numeric method using the piecewise-uniform MFBG model.2. Using the simulation model of non-uniform MFBGs, the parameters of MFBG are obtained according to its transmission spectra. The output power change under different magnetic field is calculated and the simulation result is coincident with the experimental curve for the case with the equivalent Verdet constant of 15 rad/(T?m).3. Using the simulation model of non-uniform MFBGs, the transmission characteristics of MFBGs and the MFBG-based Michelson/M-Z interferometer are analyzed. The application of the Michelson interferometer in magnetic field measurement is studied in detail by the phase compensation method. It shows that, the linearly chirped MFBGs possess the higher magnetic-field sensitivity than the uniform or apodized MFBGs, and the magnetic sensitivity can be effectively improved by optimizing the linear chirp parameter.4. The MFBG-based Sagnac interferometer(MSI) is studied, and transmittivity expression is put forword. The polarization-dependent loss (PDL) of MSI is analyzed in detail. The effects of peak PDL on uniform MFBG and gaussian apodized MFBG are compared. Simulation results indicate that the magnetic field sensitivity of the MSI system can be improved by optimizing the coupling coefficient and the available maximum peak PDL is up to 3 times that of the single MFBG.