Ultra-High Capacity Transmission in Anti-Resonant Hollow Core Fiber

Anti-resonant hollow core fiber (AR-HCF) is a promising alternative for next-generation optical systems, given their theoretical potential of achieving low loss and ultra-low Rayleigh backscattering over ultra-wide bandwidth, ideally overcoming the bottleneck of SSMF-based systems. This paper studies the Rayleigh backscattering characteristics of AR-HCF and interconnection technologies for HCF-SMF, which are of great significance to integrate AR-HCF with the existing SSMF-based network and thus enhance the system capacity by utilizing direction as a new dimension. We also report on the experimental demonstration of high-capacity same-wavelength bidirectional coherent wavelength division multiplexing (WDM) transmission over 11.04-km continuous long-length AR-HCF of the nested anti-resonant nodeless type. By leveraging low Rayleigh backscattering of AR-HCF, we achieved bidirectional transmission across the S+C+L bands (2 × 156-nm bandwidth) utilizing probabilistic constellation shaping 256QAM, with a net GMI throughput of 251.4 Tbit/s in one direction and 251.2 Tbit/s in the opposite direction. The results show an enormous potential for ultra-high capacity transmission using AR-HCF.