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Feature Articles: Keynote Speeches and R&D on Access Networks Presented at Tsukuba Forum 2025 Vol. 23, No. 9, pp. 20–26, Sept. 2025. https://doi.org/10.53829/ntr202509fa2 Looking Ahead to the Next Five YearsAbstractSince the announcement of the Innovative Optical and Wireless Network (IOWN) concept five years ago, the All-Photonics Network (APN) has been commercialized, and IOWN optical computing is being presented at the Expo 2025 Osaka, Kansai, Japan. This article looks back at the progress made to date and introduces the creation of new value and evolution of technologies toward the further development of IOWN. The content of this article is based on a keynote speech delivered by Katsuhiko Kawazoe, former NTT representative member of the board and senior executive vice president (currently chief executive fellow), at Tsukuba Forum 2025 held on May 15th–16th, 2025. Keywords: IOWN, photonics-electronics convergence, quantum technology  1. The origins of IOWN—the possibilities of lightTo humans, the petals of the evening primrose flower are quite beautiful, but to honeybees, it is the nectary gland that makes an impression. This can be explained by the concept of Umwelt, a German word meaning “environment,” which states that all living things perceive the world through their own unique set of senses. Umwelt can provide valuable suggestions on how to solve issues faced by modern society. We have been saying since the inception of the Innovative Optical and Wireless Network (IOWN) that we should learn more about differences in values and make good use of those differences within our society. Looking back over these last five years, I truly feel that this viewpoint is the essence of IOWN (Fig. 1).
The appearance of the Internet transformed the world from competition in refining the “quality” of products and services to a strategy of expansion in terms of “quantity.” This was a world in which the difference between winning and losing came down to how many terminals and users could be connected to products and services using a single protocol such as the Transmission Control Protocol/Internet Protocol (TCP/IP). However, the stage at which we can continue to measure everything by the same scale is now coming to an end. From here on, I believe that recognizing each other’s values and incorporating a diversity of values holds the key to creating a society of well-being. In short, there is a need for a transition from “quality” and “quantity” to a “logic of values” centered on a diversity of values. A huge amount of data processing and computing power will be needed to support the implementation of diverse values. The rapid progress made in generative artificial intelligence (AI) is also posing a new problem as the demand for power escalates. In 2019, we proposed the IOWN concept centered on light as a technological foundation for achieving both innovation and sustainability. Electrical signals consume an increasing amount of power as transmission distance or frequency increases; in contrast, optical signals are hardly affected by such changes. Over the last 40 years, NTT has achieved a millionfold increase in transmission capacity through optical fiber. To keep up with ever-increasing demand, we are working to introduce light into the domain of data processing beyond its use in transmission. In 2019, the NTT Group developed a transistor that could operate at 1.6 femto-joules per bit, which is approximately 1/100 the power of current transistors. This is the origin of IOWN. Another success was the establishment of technology for fabricating optical semiconductors with membranes (thin films) as an initiative toward data processing by optical means. This is a technique that forms thin films in the lateral direction as opposed to a conventional laminated structure. It can more efficiently secure optical paths and achieve further reductions in power consumption. NTT has obtained about 50 patents in relation to this photonics-electronics convergence (PEC) technology. The establishment of this technology also helped to trigger the development of the IOWN concept. 2. Five years of progress—from concept to implementationIOWN consists of multiple technical areas including the All-Photonics Network (APN), Digital Twin Computing (DTC), and PEC devices. DTC is one mechanism driving AI, and we are working to construct a new network centered on the APN and extend the use of light from only within the network to within computers through PEC technology. Through this effort, we are setting a 100-times improvement in power efficiency, 125-times increase in transmission capacity, and a 1/200 end-to-end delay as targets while making the future vision of IOWN more concrete in terms of actual technologies. Device development in support of this vision is progressing steadily. We completed an optical module for connecting datacenters in 2020 and have begun to implement it. We also completed the first phase of device development for board-to-board connections and are using such a device at the Expo 2025 Osaka, Kansai, Japan. We are constructing an optical waveguide for chip-to-chip connections and eventually intra-chip connections, and by replacing conventional electrical connections with this waveguide, we aim to develop technology that reduces power consumption to 1/100 its current level (Fig. 2).
2.1 All-Photonics NetworkAlthough optical fiber is being used in today’s Internet, the communications that flow through it are all controlled by a single protocol called the TCP/IP. The fact that light consists of multiple wavelengths has much potential, and it is technically feasible to allocate different wavelengths depending on the application. The NTT Group provides a service for delivering terrestrial digital broadcasting through optical fiber, but with IOWN, we would like to further expand the diverse possibilities possessed by light. Communications that pass through optical fiber must also pass through routers along the way, and a delay cannot help but be generated at such devices. With IOWN, we are constructing a network that can sufficiently accommodate services for which delay time would be a problem by enabling a configuration that connects light directly in an end-to-end manner. In March 2023, NTT EAST and NTT WEST began the provision of APN IOWN 1.0 as the first phase of IOWN commercial services (Fig. 3). In March 2024, NTT Communications launched an inter-prefectural APN connection service, and in November 2024, NTT EAST and NTT WEST launched All-Photonics Connect powered by IOWN as the world’s fastest user-to-user APN connection.
As an international connection, we activated a long-distance connection of approximately 3000 km with an ultra-low-latency of only 17 ms between Japan and Taiwan in August 2024. This circuit is also being used at Expo 2025. We also introduced commercial APN connections between datacenters in Mumbai, India. Interconnecting datacenters by the APN makes it possible to support use cases that require business continuity as in the fields of finance and FinTech. The application of the IOWN APN is progressing in multiple fields such as medical care and broadcasting. For example, cloud-based endoscope analysis operated in collaboration with Olympus Corporation consolidates endoscope video in the cloud via the APN and provides high-accuracy analysis and processing. Demonstrations of remote production conducted with several broadcasters, such as Tokyo Broadcasting System Television, Inc. and Japan Broadcasting Corporation, have shown that costs can be dramatically lowered by reducing the large amount of relay equipment and large number of personnel traditionally needed at stadiums and other venues and by directly transmitting video from stadium cameras to the broadcasting station. In this regard, we have obtained a high degree of interest and support from multiple broadcasters. In verification experiments conducted with Medicaroid Corporation on controlling the hinotoriTM remote surgery robot in actual connections between hospitals, the low jitter and overall stability of the APN was highly rated. These activities are showing that the features of the IOWN APN can be highly effective even in real-world environments. We expect them to be expanded to an even greater variety of use cases. 2.2 Data-centric infrastructure: information and communication technology (ICT) platform beyond geographical limitationsWe connected two graphics processing unit (GPU) platforms in a geographically separated computing environment using the APN and tested whether training could be conducted as if all GPUs were at the same location. We found that training could be conducted with almost no loss, which became a representative result of using the low-latency property of IOWN. This was a GPU-to-GPU type of connection, but we believe that it will be possible to treat resources in different locations, as in memory-to-GPU and memory-to-memory configurations, just as if they were all part of a single computer. Achieving this capability will require even further technological developments such as the design and implementation of a new operating system that takes latency into account. Our aim is to construct an ICT platform that exceeds geographical limitations—which we call data-centric infrastructure (DCI)—by solving each of these development issues. The Ministry of Internal Affairs and Communications (MIC) and Ministry of Economy, Trade and Industry (METI) have joined forces in initiating discussions on watt-bit integration (Fig. 4). Instead of bringing energy to centralized locations, the idea is to construct datacenters in outlying regions so that energy can be used in a “local production for local consumption” manner and to transmit the information thus produced. I believe these discussions will assume the existence of IOWN.
2.3 Next-generation APN: Timely control of optical pathsWith the APN, fixed point-to-point connections are assumed. For the next-generation APN, however, we envision a network in which optical paths can be established with ease from any location only when needed (Fig. 5). We will achieve this through a mechanism that can use optical paths in an even more efficient manner by enabling plug-and-play connection with a photonic gateway, executing wavelength conversion by a photonic exchange, and executing integrated control with an APN controller.
2.4 Expo 2025 Osaka, Kansai, Japan: IOWN in actionAt Expo 2025, demonstrations of IOWN technologies were held in a form that enabled even general visitors to experience them first-hand. These include Beethoven’s Symphony No. 9 with a cast of 10,000, “Cho-Kabuki” (traditional kabuki performance with cutting-edge technology), remote control of a robotic farm tractor, Kobe Storks (professional basketball team) futuristic live viewing, remote production of a television program, “One World, One Planet” (a spectacular show combining light, sound, and technology), “Fure-au Denwa” (a new kind of communication, felt in the palm of your hand), autonomous-driving-bus support, “Remotouch” remote relaxation system, and “newme” remote customer service. We are also incorporating an architectural interface powered by IOWN optical computing that analyzes visitors’ facial expressions in real time and dynamically reflects them in the movement of membrane structures that form the pavilion space. 2.5 Standardization and ecosystem formationSince its establishment five years ago, the IOWN Global Forum has grown to more than 160 participating companies and institutions. International standardization is also progressing in collaboration with the International Telecommunication Union - Telecommunication Standardization Sector (ITU-T), and a common technical platform is coming into shape consisting of both de facto and de jure standards. Going forward, we expect IOWN to expand as an even broader standard through a wider range of collaboration and co-creation not limited to participating organizations in the IOWN Global Forum. 3. Moving forward—the power of lightThe essence of IOWN is not simply to improve performance but to also create new value that goes beyond existing common sense. What is this new value that IOWN can help create? We can refer to it as the “power of light” (Fig. 6). Digitization is certainly important, but it is currently human-centric and follows a flow in which digital technology is to be used in a way that makes human life more efficient. However, if truth on the Earth is not only within humans but also in the universe and on the Earth itself, don’t we need to go beyond digital technology that we have so far been using for the convenience it brings? I believe that IOWN has the advantage in achieving this.
3.1 High-precision clock transmissionNTT would transmit a clock called a 64k Digital Clock Supply over the network to synchronize switching equipment installed throughout the country. However, with the coming of the Internet era, a transition was made to a system in which each device would autonomously maintain a clock, thus negating the need for clock transmission. In the future, if we are to achieve a world in which a wide variety of systems are precisely synchronized and phenomena beyond the grasp of humans are understood and controlled by computers, the existence of clocks that are significantly more precise than those of the past will be important. Light has the potential of transmitting such a clock at extremely high levels of precision. For example, an optical lattice clock can provide very precise time on the order of 10-18 seconds, and with IOWN technology, it should be possible to transmit such a clock directly as light for use at remote locations. If the transmission of such a high-precision clock can be achieved, I believe that IOWN will play a core role in advanced application fields that require ultra-high precision such as gravitational-wave observation and distributed quantum computing. 3.2 Quantum communicationTransmitting information in the form of photon entanglement could greatly improve resistance to eavesdropping and make key delivery unnecessary. I believe we must imagine and prepare for a world in which the all-photonics feature of IOWN enables information to be carried as quantum entanglement. 3.3 Optical quantum computingIt was predicted that quantum computers would become available by around 2050, but today, that date has been drastically moved forward and achieving them in the period 2030–2040 has come into view. Professor Akira Furusawa of the University of Tokyo and NTT are jointly working on an optical quantum computer. In contrast to a superconducting method that requires large-scale cooling equipment, this optical quantum computer uses photons enabling it to operate at room temperature while having excellent power-saving capabilities. It therefore holds the possibility of being a new option as a computing platform for the AI era from the viewpoint of power. I believe a future is in sight in which the current AI computational model centered on GPUs makes a transition to optical quantum computers much sooner than expected. With this future in mind, I would like to undertake the construction of a communication network in which IOWN not only serves as such a computing platform but also connects multiple quantum computers. 4. ConclusionFive years after its conception, IOWN is now in a phase of social implementation. Beginning with the provision of APN IOWN 1.0, we have been holding a variety of demonstrations and promoting co-creation activities while striving to implement new value together with partners worldwide. The role played by light in creating a society in which values of others are mutually respected and understood will become even greater in the years to come. Going forward, I would also like to develop IOWN-based business in a variety of forms in collaboration with even more people. |
