ZTE has partnered with YOFC, a provider of optical fibre preforms, optical fibres, cables and integrated solutions, to demonstrate the real-time transport of a single-wavelength 1.2Tb/s with 3W (34.8dBm) launch power over a 20km hollow-core fibre.
This achievement successfully verifies the ultra-low non-linear Kerr effect and ultra-low Stimulated Raman Scattering (SRS) effect of the hollow-core fibre system, marking a key milestone towards achieving longer-distance and larger-capacity transport over hollow-core fibre.
With continuous breakthroughs in the manufacturing process, the attenuation coefficient of hollow-core fibre is steadily decreasing. This, combined with ultra-low latency and ultra-low non-linearity, is expected to revolutionise fibre communication systems.
Using air as the transport medium, hollow-core fibre achieves a 47% higher optical signal transport speed compared to silica fibre, significantly reducing information transport latency. This improvement is particularly beneficial for latency-sensitive applications such as high-frequency trading, Data Center Interconnection (DCI), and AI large-model processing.
Additionally, due to the ultra-low energy ratio of optical signals in the glass, hollow-core fibre reduces the non-linear coefficient by 3-4 orders of magnitude compared to silica fibre. This reduction allows high-order modulation to be transmitted in the hollow-core fibre at high launch power, thereby maximising spectral efficiency and enabling long-haul (LH) transport of high-order modulation to greatly increase system capacity.
To fully verify the ultra-low Kerr non-linearity of the hollow-core fibre, ZTE employs an Erbium-ytterbium co-doped Optical fibre Amplifier (EYDFA) with a saturated output power of up to 3W, along with a single-wavelength 1.2Tb/s PS-64QAM coherent optical module, to connect the 20km (currently the longest in China) hollow-core fibre from YOFC. The Kerr non-linear penalty is tested with different launch powers. The results show that when the launch power of a single-wavelength 1.2Tb/s signal is as high as 3W, no significant non-linear penalty is observed in the hollow-core fibre system. This indicates that the hollow-core fibre system has great potential for long-haul transport of high-speed and high-order modulation.
Additionally, the Stimulated Raman Scattering (SRS) effect is a key factor restricting the transmission distance with ultra-wide bandwidth in silica fibre. In this verification, after an ultra-broadband S+C+L 19THz dummy light is injected into a 20km hollow-core fibre, the measured SRS loss spectrum shows that the extended bandwidth does not cause a significant power transfer effect. This verifies the ultra-low Raman transfer feature of hollow-core fibre, opening up a new path for the evolution of optical networks towards ultra-large capacity.
To date, ZTE has served more than 100 countries and regions with its optical network products, which are widely recognised by industry experts both domestically and internationally.
Moving forward, ZTE has committed to collaborating with global partners to further advance the standardisation and commercialisation of hollow-core fibre systems. They aim to build an intelligent digital world characterised by ultra-broadband optical paths, paving the way for a sustainable future of technological advancement.
