Fiber Bragg Grating Spectra in Graded-Index Multimode Optical Fibers

In this paper, we describe a simulation method to analyze the spectral properties of fiber Bragg gratings written in silica-based multimode graded-index fiber, and compare the simulation results with experimental spectra measured in Bragg gratings made in a commercially available graded-index silica fiber. The simulation provides the locations of the resonance wavelengths and uses the coupled-mode theory and the modal field equations to find the detail of the reflection and transmission spectra. A good agreement between the simulation and the experimental results is found.