Optimization of the refractive-index distribution of high-bandwidth GI polymer optical fiber based on both modal and material dispersions

The optimum refractive-index distribution of the high bandwidth graded-index polymer optical fiber (GI POF) in which material dispersion is taken into account was clarified for the first time. Since modal dispersion remarkably decreases by GI POF, this paper focuses on the ultimate bandwidth achieved by POF, quantitatively estimating the material dispersion as well as modal dispersion. The results indicated that the bandwidth of the poly(methyl methacrylate) (PMMA) based GI POF was dominated by material dispersion when the required data rate becomes larger than a few Gbs^-1. It was also confirmed that material dispersion strongly depends on the matrix polymer and that use of fluorinated polymer whose material dispersion (-0.078 ns nm^-1km^-1) is lower than that of PMMA (-0.305ns nm^-1Km^-1) allows for a 10 Gbs^-1 signal transmission.