Nippon Telegraph and Telephone Corporation (NTT), introduces and explains "Photonics-Electronics Convergence Technology" as a solution to the power consumption problem, as part of its new mid-term management strategy "Creation of New Value through IOWN (from concept to realization)."

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(1) Data centers: the foundation of the digital society

The amount of data generated by the digitalization of our daily lives, including telework, which has spread rapidly in the wake of the pandemic, as well as the expanding use of cloud computing and AI-based services, and even automated driving systems for automobiles, continues to increase, and the demand for such data is expected to spread even wider in the future.

Essential to maintaining our digital lives are large-scale data centers. A data center is a building built to house servers and network equipment. Inside the data center are racks for storing servers, high-speed lines for connecting to the Internet and other external networks, cooling systems, large-capacity power supplies, and all other facilities necessary for server installation. It is no exaggeration to say that data centers are the foundation of our modern society.
　But what problems might arise if data volumes keep increasing at the current rate?

(2) Will increasing data volumes lead to a global power shortage?

If data volumes continue to increase endlessly, the power consumption of data centers will become a major issue. At present, data centers consume only a few percent of the world's total power consumption, but that percentage is expected to grow, and with current technology, data centers will account for about 10% of total power consumption by 2030. With the pressure to decarbonize and become carbon neutral, the most pressing issue for data centers is how to reduce power consumption while meeting the demands of the digital society.

(3) What is the "Photonics-Electronics Convergence Technology" which is expected to solve energy problems?

Photonics-Electronics Convergence Technology is garnering attention as a technology that can help solve the power consumption problems of data centers. This technology merges circuits that handle electrical signals with circuits that handle optical signals. Traditional computers switch electricity on and off to perform calculations using binary numbers, which correspond to the numbers 1 and 0. However, electricity generates heat as it flows through a circuit. This is the reason why a personal computer gets hot when it performs complex processing. The fact that the PC gets hot means that energy is being used to generate heat that is not needed. In addition, the heat generated increases the resistance of the electrical path, which leads to a reduction in calculation speed.

Therefore, research is underway to replace calculations previously performed with electricity with processing using light. In other words, this research aims to connect the internal circuits of computers using light instead of electricity as much as possible to achieve low power consumption and low latency. Compared to electricity, light has the great advantage of consuming less energy and causing less delay. It can significantly reduce energy wastage and processing delays.
　Incidentally, optical fiber, which you might be familiar with, is an Internet connection capable of transmitting high-speed signals over long distances. This technology is already in practical use and we use it daily.

(4) Gradually introducing light into electrical processing and practical application of photoelectric fusion chips

To realize Photonics-Electronics Convergence Technology, we will gradually introduce light into the calculation chips and peripheral components in computers, which until now have been processed using electricity. The first step, targeted for 2024, is to establish a technology to connect the chips used for calculations and peripheral components using light. In the next phase in 2025, chips will be interconnected using light, and in the final phase in 2030, the goal is to achieve the practical use of chips that compute using light.

(5) The widespread use of Photonics-Electronics Convergence Technology will lead to a cleaner and more convenient future.

The widespread use of Photonics-Electronics Convergence Technology will result in energy savings of 40% or more by 2030, compared to today's state-of-the-art data centers. More data centers with cleaner and more computing power will make the Internet more convenient. In addition, as devices utilizing Photonics-Electronics Convergence Technology become cheaper and smaller, they will be incorporated into familiar products such as electric vehicles and home appliances in the future, making our lives cleaner and more convenient.

Please look forward to NTT's future business activities and research.

NTT Technology Journal
Research Development of Nanophotonics Technology for Optoelectronic Fusion Accelerators
https://journal.ntt.co.jp/article/5995

NTT R&D Website
What is an all-photonics network?
https://www.rd.ntt/iown/0002.html