Microsoft's Hollow-Core Fiber Boosts Data Transmission 45%

Microsoft's Azure Fiber research team has recently developed a new type of optical fiber that does not rely on traditional solid glass for light transmission. Instead, it uses air to transmit light signals, breaking the physical limits of signal loss in existing optical fibers and significantly enhancing data transmission efficiency. This breakthrough has been published in a top academic journal, marking a significant advancement in optical communication technology. The new hollow-core optical fiber, designed by the Microsoft team, represents a major leap forward in the field. By eliminating the need for solid glass, the fiber reduces signal loss and increases the distance over which data can be transmitted without degradation. This innovation has the potential to revolutionize data centers and telecommunications networks, enabling faster and more reliable data transmission. The development of this technology is a testament to the ongoing efforts to push the boundaries of what is possible in optical communication. The implications of this breakthrough are far-reaching, as it could lead to more efficient and cost-effective data transmission solutions. The research team's findings have been published in a top academic journal, highlighting the significance of their work and its potential impact on the industry.

The new hollow-core optical fiber is constructed from multiple layers of micrometer-thick concentric glass tubes. These tubes act as miniature mirrors, reflecting light back into the central air channel while suppressing higher-order modes. This design allows the fiber to transmit light signals through air, inert gases, or vacuum, rather than relying on solid glass. The air-filled core of the fiber has lower light absorption and scattering losses compared to traditional solid materials, enabling longer-distance transmission with minimal signal degradation. This breakthrough surpasses the physical limits of current optical fibers, significantly improving data transmission efficiency and distance.

The concept of hollow-core optical fibers is not entirely new, having been proposed as early as the 1960s. However, previous attempts were hindered by high signal leakage and losses exceeding 1dB/km, making them unsuitable for long-distance communication. The key to Microsoft's breakthrough lies in the use of a novel double-layer nested anti-resonant nodal fiber (DNANF) structure. This structure is surrounded by fine silica rings that utilize the photonic bandgap effect to effectively confine light within the air core, minimizing interactions with the material.

Researchers have demonstrated that this new fiber can increase transmission speed by 45% and extend data transmission distances without sacrificing bandwidth. At a wavelength of 1550 nanometers, the fiber achieved a loss level of 0.091dB/km, surpassing the theoretical limit of 0.14dB/km for the most advanced silica fibers. This advancement is considered one of the most significant in waveguide technology over the past 40 years. Additionally, the fiber achieves losses below 0.2dB/km across a wide spectral range of 66THz, far exceeding the performance of traditional silica fibers, which can only achieve similar results in narrow communication bands. The fiber's dispersion is seven times lower than that of traditional fibers, potentially simplifying transceiver designs and reducing network equipment power consumption.

As the demand for high-performance optical fiber products grows in fields such as AI, computing power, and big data, the advantages of hollow-core optical fibers are poised to usher in a new era of optical communication. The technology is already being applied in real-world scenarios. Lumenisity, which possesses advanced hollow-core optical fiber technology, was acquired by Microsoft in 2022. At that time, the technology's loss was still as high as 2.5dB/km. Currently, approximately 1,200 kilometers of the new fiber has been deployed in live networks, handling real business traffic. In November 2023, Microsoft introduced a new generation of hollow-core fiber technology, and in November 2024, the company announced plans to deploy 15,000 kilometers of the fiber in its Azure global network over the next 24 months, with a focus on supporting low-latency, high-bandwidth requirements for AI and high-performance computing scenarios.

With the increasing demand for data center interconnectivity driven by AI, the optical fiber industry is rapidly evolving. Beyond Microsoft, major companies worldwide are accelerating their investments in hollow-core optical fiber technology. In China, telecommunications operators are leading the way. In July 2025, China Mobile launched the country's first commercial anti-resonant hollow-core optical fiber line in Guangdong, serving cross-border financial services between China and Hong Kong. The line achieved an average loss of 0.085dB/km, with the lowest loss reaching 0.065dB/km, setting a new global commercial record. In June 2025, China Telecom's Guangdong branch and its international division issued a tender for a mixed optical cable centralized procurement project, which included a significant amount of hollow-core optical fiber. According to China Galaxy Securities, based on the highest bid limit, the current price of hollow-core optical fiber is 370,000 to 380,000 yuan per core-kilometer, a reduction of approximately one-quarter from the first bid, indicating an unexpectedly rapid adoption rate.

China Galaxy Securities noted that hollow-core optical fibers have broad applications in scenarios such as high-frequency financial trading, distributed computing centers, data center interconnects, submarine cables, industrial and medical lasers, and quantum communication. CITIC Securities expressed optimism that as hollow-core optical fiber technology becomes standardized, its scalable applications will expand to more scenarios. Domestically, companies such as Yangtze Optical Fiber, Changyuan Communication, Hengtong Optic-Electric, and Skyworth Technology have demonstrated capabilities in the research, production, and sales of hollow-core optical fibers. However, challenges remain in the commercialization process, including the need for upgrades in mass production techniques and the establishment of industry standards. Currently, the structural control of hollow-core optical fibers during production is difficult, making large-scale, long-length production challenging. Additionally, the transition from solid-core to hollow-core fibers in practical applications poses another hurdle.