Highly dispersion tailored properties of few mode fiber Bragg grating-based vibration sensor due to a perturbed apodization profile

A dispersion tailored properties of fiber Bragg grating (FBG)-based vibration sensor has been explored, assuming a highly perturbed apodization profile. Most of the FBG designed so far for vibration sensing applications are nonuniform. This paper deals with the modeling of perturbation as a more complicated chirp-type nonlinear apodization profile. It can significantly reduce the dispersion-induced signal distortion and side lobe intensity followed by the improvement of sensor performance. The study reveals that an accurate modeling of vibration sensor is quite feasible while opting the proposed apodization profile. FBG sensor parameters are optimized in such a way that the sensor may operate only under lowest order modes. To the author's knowledge, sensing capability of FBG-based microaccelerometer having arbitrary chirp type of apodization profile has not been discussed before. It is assumed that small perturbation theory is valid while keeping the influence of microbend geometry in analysis. The standard matrix method is used to study dispersion characteristics due to the complicated apodized profile. The simulation results are validated with the experimental result for the known cases. (C) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)