Optimization of Modal and Material Dispersions in High-Bandwidth Graded-Index Polymer Optical Fibers

The optimum refractive-index distribution of the high bandwidth graded-index polymer optical fiber (GI POF) was clarified by consideration of both modal and material dispersions. The ultimate bandwidth achieved by the POF is investigated by a quantitative estimation of the material dispersion as well as the modal dispersion. The results indicated that even if the refractive-index distribution is tightly controlled, the bandwidth of the poly (methyl methacrylate) (PMMA)-base GI POF was dominated by the material dispersion when the required bit rate becomes larger than 4 Gb/s for 100-m transmission. It was also confirmed that the material dispersion strongly depends on the matrix polymer and that the fluorinated polymer whose material dispersion (-0.078 ns/nm·km) is lower than that of poly methyl methacrylate (-0.305 ns/nm·km) allows for a 10 Gb/s transmission rate in 100 m link.