Innovative asymmetrical rod arrangement and rotation in 125-μm-cladding seven-core rod-assisted multicore fiber for enhanced short-reach communication in C, and L Bands

A novel seven-core hexagonal rod-assisted multi-core fiber (RA-MCF) with a 125-$\mu$m cladding diameter is proposed to achieve low crosstalk (XT) and efficient transmission across the C- and L-bands. Through the strategic use of an asymmetrical rod arrangement around the central core (C0) and systematic variation of rod positions from 0°to 120°, the design effectively disrupts uniform mode coupling pathways, significantly reducing XT compared to conventional symmetrical configurations. Analytical modeling and finite element method (FEM) simulations validate the design’s efficacy, demonstrating average XT levels of approximately -45 dB/km in the C-band and acceptable XT levels throughout the L-band. Utilizing a core pitch of 40 $\mu$m, the proposed RA-MCF achieves robust power transfer while maintaining minimal XT across both bands. The optimized fiber design adheres to ITU-T G.655 and G.656 standards, exhibiting low bending loss (0.0157 dB) and acceptable dispersion (14.4 ps/(nm$\cdot$km)) at 1550 nm. These features render the proposed fiber an ideal candidate for high-density metro networks and data center interconnects, ensuring reliable short-reach transmission with enhanced signal isolation.