Opportunities and Challenges for Long-Distance Transmission in Hollow-Core Fibres

The loss of hollow-core Nested Antiresonant Nodeless Fiber (NANF) has been steadily decreasing lately, approaching that of standard Single-Mode Fiber (SMF). As for non-linear effects, they are already three to four orders of magnitude lower than in SMF. Theoretical predictions and experimental evidence also hint at a much wider usable bandwidth than SMF, potentially several tens of THz. Propagation speed is 50%faster, a key feature in certain contexts. We investigate the potential impact of possible future high-performance NANF on optical communication systems, assuming that NANF continues on its current path towards better performance. We look at system throughput in different scenarios, addressing links from 100 km to 4,000 km, assuming different NANF optical bandwidths and loss. We found that NANF might enable throughput gains, vs. a benchmark SMF Raman-amplified C+L system, on the order of 1.5x to 5x, at reasonable system parameter values, including launch power. We also consider NANF Inter-Modal-Interference (IMI) and show that the value required for negligible system impact is about –60 dB/km, close to the currently best reported values. We finally look at more long-term scenarios in which NANF loss might get below that of SMF and we show that in this context repeaterless or even completely amplifierless systems might be possible, delivering 300400 Tb/s per NANF, over 200 to 300 km distances. While several technological hurdles remain before NANF systems become practical, NANF appears to have the potential to become an attractive and possibly disruptive alternative to conventional solid-core silica fibers.