Superposition-assisted 125-μm cladding multi-core fibers with ultra-low inter-core crosstalk and high relative core multiplicity factor

Abstract

We propose a novel superposition-assisted structure (SAS), composed of trench and air holes, in few-mode multi-core fibers (FM-MCFs) to effectively suppress the inter-core crosstalk (XT). The proposed SAS can minimize the inter-core XT to −70.58 dB/100 km in the 7-core fibers, which is 60 dB/100 km lower than the typical trench-assisted structure and 29 dB/100 km lower than the typical hole-assisted structure, respectively. In addition, the SAS does not introduce extra fiber loss and dispersion. In this paper, the key properties of SAS MCFs are numerically simulated using the finite element method (FEM). The large effective area (Aeff) over 90 μm2 enables the suppression of nonlinear effects. The values of dispersion coefficient and differential mode group delay (DMGD) are in the range of 24–42 [ps/(nm·km)] and 5–23 ps/m over C + L band, respectively, which are favorable for fiber communication systems. Such SAS 7-core 5-LP-mode fibers can be further optimized to obtain the cladding diameter of 125 μm, where five propagation modes achieve inter-core XT target below −50 dB/100 km with the bending radius less than 500 mm. Besides, the optimized relative core multiplicity factor (RCMF) can be up to 97.55. The proposed SAS provides a promising solution for the design of FM-MCFs with ultra-low inter-core XT and high capacity for space division multiplexing (SDM).