Longitudinal characterization of fiber Bragg gratings

The proposed Fiber Bragg Grating (FBG) sensor investigated spectral features applying finite element numerical (FEM) analysis method. The wave optics module applied the Maxwell’s equations and confined the electromagnetic perfectly. The best optimized chosen parameters are 1.45, 1.5 for clad and core refractive indices, respectively, for a better FWHM of 20 nm approximately with the highest reflectivity of 93.5%. As a sensor, the FBG is developed in a D form with optimum specifications. An etched FBG's sensitivity to the surrounding medium's refractive index (RI) has been documented. For the analyte index (AI) range of 1.3–1.39 by 9 um etching diameter, the optimal wavelength sensitivity (WS) and resolution are 118.7 nm/RIU and 1 × 10−3 RIU, respectively.