In September 2025, Nature Photonics published a heavyweight achievement: the microstructure hollow core fiber (Hollow Core Fiber) jointly developed by Microsoft Azure Fiber team and the University of Southampton in the UK achieved ultra-low loss of 0.091dB/km at 1550nm communication wavelength, bringing fiber loss below 0.1dB/km for the first time, reducing the theoretical limit of traditional quartz fiber by about 35% and increasing transmission speed by 45%.

The core of the fiber optic cable is an air channel surrounded by a precision silicon dioxide microstructure ring, which utilizes the photonic bandgap effect to constrain the optical signal, with almost no dispersion or signal distortion. It is suitable for high-end scenarios such as long-distance backbone networks, AI computing power cluster interconnection, and quantum communication. Microsoft has deployed over 1200 kilometers of experimental networks and plans to expand to 15000 kilometers within two years.