Japan Breaks World Record with 402 Tbps Internet Speed Using Standard Fiber Cables!

The contemporary digital landscape is defined by an ever-accelerating demand for data, driven by the proliferation of advanced internet applications and services. This insatiable appetite for bandwidth is rapidly pushing the limits of existing optical fiber networks, leading to what industry experts refer to as a “capacity crunch”.1 Optical fiber networks form the fundamental backbone of modern communication, responsible for transmitting an astounding 99% of global internet data traffic.2 As digital services evolve and become more complex, the primary constraint on performance is increasingly shifting from raw computational power or local storage capabilities to the interconnecting network fabric itself. The ability to move vast quantities of data at unprecedented speeds across networks is becoming paramount, particularly for distributed computing paradigms and the burgeoning field of artificial intelligence.

Against this backdrop of escalating demand, an international research team, spearheaded by Japan’s National Institute of Information and Communications Technology (NICT), announced a monumental achievement in March 2024. They established a new world record for internet speed, achieving a staggering 402 terabits per second (Tbps).3 To contextualize this immense speed, it is sufficient to download a complete operating system in less than a millisecond, or approximately 50,000 full high-definition (HD) movies in a single second.11 This breakthrough significantly surpasses previous records, including Japan’s own 319 Tbps in 2021 and University College London’s 178 Tbps in 2020, underscoring the rapid advancements in optical communication technology.5

A pivotal aspect of this record-breaking feat is that it was accomplished using standard commercially available optical fiber.3 This detail is not merely a technical specification; it carries profound economic and logistical implications. The technology is inherently compatible with the vast global network of fiber optic cables already deployed underground and beneath oceans.12 This compatibility suggests a pathway to capacity upgrades that does not necessitate the costly and disruptive process of replacing existing physical infrastructure. By extending the operational lifespan of current fiber systems, this innovation offers a potentially significant benefit in the near term, providing additional transmission capacity without the substantial capital expenditure typically associated with new fiber deployment.3 Such an approach could help stabilize broadband prices despite the relentless increase in data demand 6, making commercialization significantly more feasible.

To provide a historical perspective on the rapid progress in optical fiber transmission, the following table illustrates key milestones:

II. The Engineering Marvel: How 402 Tbps Was Achieved

This monumental achievement is the culmination of a truly international and interdisciplinary effort. The core research was led by the Photonic Network Laboratory of Japan’s National Institute of Information and Communications Technology (NICT), with substantial contributions from a global consortium including Aston University (UK), Nokia Bell Labs (USA), Amonics (Hong Kong), the University of Padova (Italy), and the University of Stuttgart (Germany).3 Key figures in this collaborative endeavor include Ben Puttnam, chief senior researcher at NICT, and Dr. Ian Philips from Aston University.6 The involvement of multiple institutions across different continents underscores that breakthroughs of this magnitude often require the pooling of diverse expertise, resources, and perspectives, demonstrating a collaborative model increasingly prevalent in advanced scientific and engineering research.

The fundamental innovation behind the 402 Tbps record lies in the revolutionary utilization of the optical fiber’s full spectral potential. Historically, commercial fiber optic connections have predominantly relied on only one or two wavelength bands, typically the C and L bands, which offer the most stable transmission with minimal data loss.7 The capacity limit within these conventional bands is generally considered to be around 100 Tbps.7 The research team, however, constructed the first optical transmission system capable of covering all six low-loss transmission bands of standard optical fibers: O, E, S, C, L, and U.3 By expanding the usable optical spectrum to an aggregate 37.6 THz (equivalent to a 275 nm optical bandwidth), the team successfully enabled more than 1,500 parallel transmission channels.3 This represents a significant 35% increase in aggregate transmission bandwidth compared to previous records.3 This approach signifies a strategic shift in capacity scaling: rather than solely focusing on increasing spectral efficiency within existing narrow bands, the breakthrough primarily leverages previously unutilized “spectral real estate” within the fiber. This strategy aims to maximize the total available bandwidth across the fiber’s entire low-loss spectrum, paving a new path for future capacity growth.

To harness these newly accessed wavelength bands, the system incorporates a suite of sophisticated amplification and signal processing technologies, some of which were specifically developed for this demonstration. These include:

• Six distinct variants of doped-fiber optical amplifiers (DFAs) providing gain across the O, E, S, C, and L bands.3 Notably, Aston University played a crucial role by developing U-band Raman amplifiers, addressing a spectral region where conventional doped fiber amplifiers are not yet commercially available.6
• The integration of both discrete and distributed Raman amplification.3 Raman amplification is a vital technology due to its broad bandwidth compatibility, low noise characteristics, distributed gain capabilities, and remarkable wavelength flexibility. It can amplify signals across a wide range of wavelengths, including the S, C, L, and even the U-bands.15 Furthermore, Raman amplification avoids the need for optical-to-electrical-to-optical (OEO) conversions, thereby simplifying the system architecture and reducing potential points of signal degradation.16
• The deployment of novel optical gain equalizers.3 These devices are indispensable for maintaining signal integrity across the wide spectrum. They continuously monitor each wavelength channel and selectively adjust its amplitude to flatten the optical power spectrum, effectively counteracting the uneven gain characteristics inherent in amplifiers and filters. This precise management of signal power significantly improves the signal-to-noise ratio over long transmission spans.17

The system also employed advanced modulation formats, such as dual-polarization 256-QAM, 64-QAM, or 16-QAM, applied to multi-wavelength light to simulate independent data streams.3 While the theoretical maximum data-rate, estimated using Generalized Mutual Information (GMI), was 402 Tbps, the practical decoded data-rate after applying standard error correction codes was 378 Tbps.3 The detailed list of these amplification and equalization technologies reveals that simply opening new wavelength bands is insufficient; these bands often exhibit higher loss rates 13 and are susceptible to complex non-linear effects like Inter-Channel Raman Scattering (ISRS) and Kerr nonlinearity.2 The development of sophisticated, multi-variant amplifiers and precise gain equalizers represents a significant engineering triumph, enabling the active management and compensation of these physical impairments across a much broader optical spectrum. This underscores that the achievement is as much about advanced signal conditioning and active network management as it is about raw bandwidth.

The “standard fiber” aspect of this breakthrough is of paramount importance for its scalability. The 402 Tbps speeds were achieved on single-mode fiber (SMF) with a standard cladding diameter of 0.125 mm.7 This standard diameter is critical because the vast majority of the existing global fiber infrastructure, along with the entire ecosystem of manufacturing, tooling, connectorization, and deployment reliability, is built around this specific dimension.22 It is important to distinguish this achievement from advancements in multi-core fiber (MCF) technology, which represents another promising avenue for capacity increase through Space Division Multiplexing (SDM).23 While NICT has also achieved impressive Peta-bit speeds using MCF 26, the 402 Tbps record on standard single-mode fiber offers a more immediate and less disruptive upgrade path for existing networks. This is because it primarily involves upgrading the active components, such as amplifiers and transceivers, at the ends and along the line, rather than requiring the replacement of the physical fiber itself.

The following table summarizes the key technical parameters of this groundbreaking achievement:

A Glimpse into Tomorrow: Applications and Transformative Impact

The advent of ultra-high-speed internet, exemplified by the 402 Tbps breakthrough, is poised to profoundly reshape numerous sectors and applications, with Artificial Intelligence (AI) at the forefront. The escalating growth of AI and deep learning models demands unprecedented levels of data processing and transfer, creating a critical need for seamless, high-speed connectivity between processors, Graphics Processing Units (GPUs), and cloud storage.28 Current AI infrastructures already require approximately 1 Tbps of network bandwidth per accelerated processing unit (xPU), a figure that is projected to quadruple every two years.29 This exponential demand means that network constraints, rather than raw computational power, are increasingly becoming the most significant impediment to AI profitability. For instance, Meta reported that its early AI applications spent a third of their operational time simply waiting on the network.29 Ultra-high-speed optical networks are therefore essential for supporting the trillions of transactions and complex cloud-based learning models that define the future of AI.28 They will enable real-time learning applications, instantaneous data transfers, and the efficient operation of massive AI computing clusters.28 This highlights AI as not merely a driver, but arguably the most significant and urgent catalyst for the next generation of optical network upgrades, creating an imperative for these breakthroughs to transition from laboratory to widespread deployment.

Beyond AI, the transformative impact of such speeds extends to immersive digital realities. The ability to transmit data at 402 Tbps is a game-changer for virtual reality (VR) experiences that feel truly real and augmented reality (AR) applications that seamlessly integrate digital content with the physical world.30 These speeds will enable the smooth streaming of 8K videos without interruptions and provide the immense bandwidth required for the ultra-HD graphics and real-time data processing inherent in these immersive applications.30

The societal advancements enabled by this level of connectivity are far-reaching, impacting critical sectors such as telemedicine, remote education, smart infrastructure, and the Internet of Things (IoT):

• Telemedicine: Real-time consultations become truly feasible, alongside the rapid transfer and processing of large volumes of medical imaging data with virtually no latency, regardless of geographical location.30
• Education: Students can participate in virtual classrooms with zero lag, making education more accessible and interactive, fostering new pedagogical approaches.28
• Businesses: Operations can achieve unprecedented efficiency through seamless video conferencing, instant data transfers, and highly responsive cloud services.30
• Smart Infrastructure & IoT: Ultra-high-speed networks are crucial for supporting the vast networks of interconnected devices and the real-time data processing required for autonomous systems, including self-driving cars, drone deliveries, and smart city management.32

Beyond raw speed, high-speed optical communication offers substantial advantages in energy efficiency and enhanced security. Optical signals experience less attenuation than electrical signals, resulting in reduced power loss during long-distance transmission.31 Furthermore, optical devices generate less heat compared to their electrical counterparts, which can significantly reduce the cooling demands in data centers, potentially leading to energy savings of 30% or more under certain conditions.31 This demonstrates that the development of ultra-high-speed optical networks is not solely about performance, but also about building a more sustainable digital infrastructure. In terms of security, optical signals are highly compatible with advanced encryption methods, holding significant potential for the future implementation of quantum cryptography communication over optical fibers, thereby offering unparalleled and theoretically unbreakable security.31 These benefits highlight the holistic value proposition of such advancements, addressing critical long-term considerations for global networks.

The following table summarizes the profound impact of ultra-high-speed fiber optics on key digital sectors:

The Road Ahead: Challenges and Future Prospects

While the 402 Tbps record represents a monumental laboratory achievement, its translation into widespread commercial deployment faces several technical hurdles. Pushing data transmission across ultra-wideband (OESCLU) exacerbates complex non-linear optical effects, such as Inter-Channel Raman Scattering (ISRS) and Kerr nonlinearity.2 These physical phenomena fundamentally limit achievable information rates and necessitate intricate optimization of system parameters, including launch power, along with advanced signal processing techniques.2 Achieving homogeneous performance in long-haul wideband transmission is particularly challenging due to these effects, as well as amplifier gain ripple and limitations of components specific to certain bands.20 The path to commercialization is not merely about scaling up the lab setup; it involves mitigating these complex physical impairments that become more pronounced at higher capacities and wider bandwidths. This suggests that the “last mile” to commercial deployment involves overcoming intricate engineering and physics challenges related to signal integrity and component performance, rather than solely economic or logistical ones.

Another significant challenge lies in the maturity and cost of the necessary optical components. While the fiber itself is standard, the optical amplifiers and other critical components, such as optical cross-connects (WSS), required for the newly utilized O, E, S, and U bands are currently less developed and often suboptimal compared to those designed for the conventional C and L bands.21 Developing robust, cost-effective, and high-performance components specifically for these wider bands is crucial for widespread adoption.35 Furthermore, managing chromatic dispersion across such a broad spectrum, along with addressing the complexity of multiplexing equipment and ensuring the stability of light sources, remains a technical hurdle.21

Economic considerations also play a significant role in the commercialization timeline. The high cost and suboptimal performance of multi-band optical amplifiers, owing to their underdeveloped state, currently represent a notable barrier to field implementation.14 While multi-band systems offer the advantage of reducing the need for new fiber deployments, thereby postponing large capital expenditures 3, the overall cost-effectiveness is heavily dependent on the price of these new multi-band amplifiers and the projected network capacity requirements.14 For example, O-Band Fiber Amplifiers can range in cost from approximately $13,000 to $18,000 per unit 36, and a typical Erbium-Doped Fiber Amplifier (EDFA) consumes around 50W of power.37 The economic viability is therefore a delicate balance between the capital expenditure saved on fiber deployment and the new operational and capital expenditures associated with advanced, multi-band active components. If fiber costs remain minimal or additional fibers are readily available, C-band-only systems may continue to be the most economical choice.14 A “pay-as-you-grow” approach, where additional bands are gradually enabled as traffic loads increase and component costs decrease, is a likely strategy to manage these financial considerations.14

Both NICT and Aston University are actively engaged in ongoing research to further push the boundaries of optical communication. NICT’s roadmap includes continued research and development into novel amplifier technologies, components, and fibers to support new transmission windows.7 Their objectives include extending the transmission range of these ultra-high-capacity systems and ensuring their compatibility with existing field-deployed fibers.7 NICT is also laying the groundwork for “Beyond 5G” and “6G” services in the 2030s, which includes the critical integration of quantum communication technologies to enhance security.27 Ben Puttnam of NICT has indicated that speeds of up to 600 Tbps could be attainable with existing cables through further optimization of channels and filling in spectral gaps.12 Moreover, NICT is a leader in Space Division Multiplexing (SDM) using multi-core fibers, having achieved a remarkable 22.9 Peta-bits per second (Pbps) in a single fiber.26 This demonstrates that the future of optical communication capacity is not confined to a single, linear path; research is pursuing multiple, complementary strategies—including ultra-wideband WDM on standard single-mode fiber, Space Division Multiplexing with multi-core fibers, and advanced dynamic amplification—to address the escalating demand. Each approach presents its own set of advantages and challenges, contributing to a robust long-term roadmap for network evolution.

Aston University’s contributions include the development of advanced amplifier designs, such as Bismuth-Doped Fibre Amplifiers (BDFAs) for the S- and E-bands 38, and research into Raman fiber amplifiers and Fiber Optical Parametric Amplifiers (FOPAs) for their near-instantaneous response times, which are crucial for managing dynamic network traffic patterns.1 They are also actively working on mitigating non-linear effects in optical transmission through innovative techniques like optical phase conjugators.1

Despite these advancements, the widespread commercial deployment of 402 Tbps speeds for general internet users is not immediate. This technology is primarily aimed at enhancing the core backbone networks and inter-data center links, where aggregate bandwidth is paramount.11 The focus is on extending the lifespan of existing fiber systems and meeting the anticipated demands of “Beyond 5G” and “6G” services in the 2030s.7 For consumer “last mile” connections, current commercial deployments are seeing rapid growth in Fiber-to-the-Home (FTTH), with 10 Gbps (XGS-PON) becoming an industry standard and explorations into 25G PON and even 100G PON underway.39 This tiered approach to network upgrades implies that while core network capacities will expand dramatically, the direct application of 402 Tbps to individual homes is not the immediate objective. Consumer speeds will gradually increase as these core network capacities expand and new access technologies mature.

Conclusion: Building the Backbone of the Digital Age

The achievement of 402 Tbps data transmission by NICT and its international collaborators is a profound testament to the relentless pace of innovation in optical communications. This is far more than a mere numerical milestone; it represents a strategic advancement poised to fundamentally reshape the digital infrastructure that underpins our modern world.

By demonstrating the feasibility of ultra-high-speed data transmission over existing standard fiber, this breakthrough offers a viable and economically attractive pathway to address the escalating demands of artificial intelligence, immersive technologies, and the ever-expanding Internet of Things. The ongoing research into advanced amplification, comprehensive multi-band utilization, and complementary technologies like multi-core fiber, coupled with a keen focus on energy efficiency and security, paints a compelling picture of a future internet. This future network promises to be not only significantly faster but also inherently more robust, sustainable, and secure. The 402 Tbps achievement lays a critical foundation for the next generation of global connectivity, ensuring that the digital future remains boundless and resilient.