Crosstalk and Core Density in Uncoupled Multicore Fibers

Reduction of intercore crosstalk in uncoupled multicore fibers (MCFs) is the most critical issue for long-haul space division multiplexing transmission. The required coupling coefficient, allowable outer cladding diameter, and assumed bending radii range are important fiber design parameters for maximizing a relative core density while maintaining low-crosstalk level in an MCF. The relationships between crosstalk and core density in uncoupled MCFs with a step-index profile and trench-assisted structure are investigated in detail, and the maximum achievable relative core multiplicity factors are clarified in a limited cladding diameter.