Maximizing the Capacity of Graded-Index Multimode Fibers in the Linear Regime

Abstract

In this paper, we investigate the design of multimode fibers (MMFs) guiding over 1000 spatial modes. A trench-assisted graded-index core profile is optimized for low differential mode delay (DMD) over the C-band. The optimization results show that for a maximum DMD of 250 ps/km as much as 400 spatial modes can be supported ideally. It is shown that the optimized DMD scales with the number of modes before it reaches a plateau for a given core-cladding contrastindicating that maximizing the core radius can allow to increase spatial cardinality without significant delay spread increase. Closed-form equations for optimal refractive-index profile parameters are introduced. The throughput supported by the optimized fibers is studied and the scaling trend with the number of guided modes is analyzed for increasing core-cladding contrast. Throughput is shown to be significantly impacted by Rayleigh scattering, macro-bend loss and coating loss, introducing a practical limit to the scaling of the number of modesat approximately 1000 spatial modes. Here dubbed as the half-mode number, it corresponds to the number of modes beyond which the extra throughput per additional mode decays to half of that of the best mode. Finally, the impact of the fabrication margins on the DMD of the optimized profiles is analyzed.

Modal Dynamics for Space-Division Multiplexing in Multi-Mode Fibers

“…pace-division multiplexing is one of the advanced technologies being considered to fulfil the increased demand of information transfer where data copropagates in the parallel spatial pathways making the use of shared resources [1][2][3][4][5] and which includes parallel cabled single-mode fibers, multi-core fibers (MCFs), multi-mode fibers (MMFs) as well as few-mode multi-core fibers. MMFs allow for tenths-to-hundreds of spatial pathways while keeping to a standard cladding diameter of 125 μmallowing for higher production yield and smaller mechanical failure rates [6][7][8]. While coupled-core MCFs allow for only ~19 spatial pathways [2] when keeping to a standard cladding diameter.…”