Design and Simulation of Apodized π-Phase Shifted FBG as Simultaneous Sensing of Strain, Temperature, and Vibration

Bragg Gratings (FBGs) in Structural Health Monitoring (SHM) are used as an optical sensor to detect various physical phenomena to make the system more reliable and accurate. In this work, theoretical analysis and numerical simulation of an Apodized π-Phase Shifted Fiber Bragg Grating (π-PS FBG) sensor is proposed to evaluate the performance of this non-uniform FBG for simultaneous strain, temperature, and vibration sensing. Due to the accuracy and spectral characteristics of π-PS FBG, it's chosen as an optical sensor to enhance the sensibility measurements. The sensor signals designed and simulated by solving coupled mode equations using transfer matrix method in MATLAB to represent the reflected spectrum of PS FBG. As a spectral improvement purpose, the Gaussian apodization function is applied on FBG reflection spectrum to optimize spectra by supressing side lobes. Lastly, the reference FBG method calculation is used to separate vibration and temperature effects from the strain measurements.