Low-DMD and low-crosstalk few-mode multi-core fiber with air-trench/holes assisted graded-index profile

Abstract

We propose a novel scheme of air-trench (AT) assisted graded-index profile to design a heterogeneous few-mode multi-core fiber (hetero-FM-MCF) with high density of cores and low inter-core crosstalk (XT). By the using of finite element method (FEM), it is revealed that the AT structure can remarkably reduce XT and bending loss, and leaving no significant impact on other fiber properties. The numerical analyses show that the AT hetero-FM-MCF achieves a low XT of about -66 dB/km (15.7% lower than that of trench-assisted (TA) hetero-FM-MCF), the max differential model delay (DMD) over C+L band of 70 ps/km and relative core multiplicity factor (RCMF) of 41.7. To further improve the light confinement ability of individual cores, air-holes (AH) are introduced to the AT structure. The air-trench/hole assisted (AT-AH) hetero-FM-MCF generates a lower XT of -68 dB/km and 6% bending loss values optimization than AT hetero-FM-MCF.