Results of fiber Bragg grating writing on silica graded-index multimode optical fibers of different generations

This work is concerned on comparative analysis results of fiber Bragg grating (FBG) writing on silica telecommunication multimode optical fibers 50/125 of different generations. We overviewed known techniques for FBG writing and selected one based on Lloyd interferometer for FBG preparing on multimode optical fibers differing by graded refractive index profile and large core diameter in comparison with standard single mode optical fibers. A set of 48 FBG samples was prepared on four multimode fibers 50/125 with preliminary measured refractive index profiles. Two of them were first generation fibers of TIA/EIA Cat. OM2 with great defects of refractive index profile at the core center (deep and peak) and strong refractive index fluctuations. Another two fibers were laser-optimized multimode fibers of Cat. OM2+/OM3. Here one graded refractive index profile was clear while second contained thin peak in the core center. Results of FBG spectral response comparison are represented.