Ge-Free Ring-Core Fibers: New Opportunities for Short-Reach WDM-MDM Systems

For achieving low intrinsic losses of LP-mode-groups in radially-single-mode ring-core fibers, we propose to adopt a Germanium-free (pure-silica/fluorine-doped) ring-core. Calculated effective-index-differences, group-velocity-dispersions, differential-group-delays, and effective-areas suggest that these fibers are suitable for short-reach WDM-MDM systems.