Rescaled Multimode Fibers for Mode-Division Multiplexing

Graded-index-core multimode fibers can be appropriately rescaled in diameters and adjusted in alphas to exhibit low differential mode group delays for 15, 21, and 28 spatial modes (five-, six-, and seven-mode groups, respectively). The fibers are actually designed to support six-, seven-, and eight-mode groups but their last mode group is neglected, which reduces the impact of cladding and the sensitivity to process variability, and, thus, allows to dramatically decrease the differential mode group delays. An eight-mode-group rescaled multimode fiber is fabricated. Differential-mode-group delays <;90 ps/km are obtained for the first seven mode groups (28 spatial modes), which is equivalent to those of ten-spatial-mode fibers.