Bend Performance Analysis of Few-Mode Fibers With High Modal Multiplicity Factors

This paper presents a comprehensive and detailed investigation on the bend-induced characteristics of the most advanced few-mode fibers (FMFs) that allow one to multiply the capacity of single-mode fiber transmissions by a high factor (≥12), suitable for dense mode-division multiplexing (MDM) systems. To be specific, we numerically demonstrate how bend can affects the normalized propagation constant, modal field distribution, bend loss, and effective area of all supported spatial LP modes, for both the weakly coupled step-index (SI) 7-LP-mode fiber (adapted to weakly coupled MDM systems with a modal multiplicity factor of 12) and the trench-assisted graded-index (GI) low-differential-mode-group-delay 9-LP-mode fiber (adapted to strongly coupled MDM systems with a modal multiplicity factor of 15). Also presented are the empirical relations of normalized spatial density for the above two FMFs at different bend radii. Finally, for weakly coupled SI FMFs and GI low-DMGD FMFs, we reexamine their design strategy and scalability depicted in [4], from a unique perspective of bend performance.