Easy‑to‑understand principle: In traditional optical fibres, light propagates within a solid‑glass core. A hollow‑core fibre confines light inside an air‑filled core with the help of its micro‑structured cladding. Given the refractive index of air is close to 1, it overcomes the physical limitations imposed by silica glass.

The refractive index of common glass fibre stands at around 1.45, which slows down light speed to roughly 200,000 km/s and brings latency of about 5 μs per kilometre. With air at a refractive index near‑unity, light travels at 99.7% of the speed of light in vacuum, yielding latency of merely 3.34 μs/km. One‑way latency is cut by approximately 31%, and round‑trip latency is reduced by one‑third. The 110‑kilometre cross‑border hollow‑core‑fibre link built by YOFC connecting the Dongguan and Hong‑Kong stock‑exchange data centres achieves a record‑low round‑trip latency of 0.93 ms. This fibre suits latency‑sensitive services including stock trading, AI supercomputing clusters, high‑frequency transactions and cloud gaming.

Commercial‑grade standard G.652‑D fibre features an attenuation loss between 0.18 and 0.22 dB/km. Mass‑produced anti‑resonant hollow‑core fibre has hit a world‑record‑breaking minimum attenuation of 0.04 dB/km set by YOFC, outperforming conventional ultra‑low‑loss G.654‑E fibre. Benefit: No intermediate optical amplifiers are required for 100‑km‑plus single spans. It simplifies infrastructure for long‑haul trunk lines, submarine cables and cross‑border leased lines while cutting equipment power consumption and maintenance costs.

Silica‑based fibre suffers from severe Kerr nonlinearity and four‑wave mixing that cap the single‑wavelength data rate. Since the overwhelming share of optical energy travels inside the air core, light barely interacts with glass, and nonlinear effects are weakened by tens of thousands of times. The world’s first field‑deployed test of 1.2 Tb/s single‑wavelength unrepeated long‑span transmission over hollow‑core fibre has been completed. The fibre readily accommodates 800 G and 1.6 T ultra‑high‑speed channels as well as S‑band, C‑band and L‑band multi‑band backbone networks tailored for next‑generation computing‑power bearing infrastructure.

Intense laser radiation may burn or damage a solid glass core, whereas air absorbs negligible luminous energy. Hollow‑core fibres are capable of carrying high‑power laser beams. Beyond telecommunications, they find applications in industrial lasers, lidar and aerospace sensing hardware.

It is hard to balance material dispersion and waveguide dispersion within traditional fibres. Engineers can tune the micro‑structured cladding of hollow‑core fibres to optimise dispersion profiles and attain flat dispersion across a broad spectral range. High‑speed signals suffer little waveform degradation after long‑haul travel, removing the need for dispersion‑compensating fibre.

As light signals propagate chiefly through the air cavity, performance is scarcely affected by glass defects and impurity scattering. Hollow‑core fibres feature heat resistance and radiation endurance with minor performance degradation under high‑temperature conditions or heavy cosmic radiation in space. Their bend‑induced loss stays well under control and outperforms that of traditional special‑purpose optical fibre when bent during field installation.