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December 12, 2023


Spatial Division Multiplexing and IOWN: the Future of Optical Communication

Optical fiber-based communication infrastructure is becoming the backbone of our modern digital existence. With the coming of 6G wireless communications and an array of modern services such as video streaming, autonomous driving, and generative AI, the appetite for data is only set to grow. This creates a huge challenge for optical communication systems, which are now under pressure to multiply their transmission capacities.

NTT is at the forefront of this challenge, pioneering research and development to sustainably boost optical fiber communication capacity. Its latest breakthrough? Balancing increased transmission capacity with reduced power consumption. That almost sounds too good to be true, doesn't it?

It's all thanks to spatial division multiplexing (SDM) technology. By integrating a multicore structure for collective optical amplification, NTT has been able to not only transmit more, but do it while using less power.

SDM's essence lies in its ability to use multiple spatial pathways within a single medium, like an optical fiber, enabling simultaneous transmission of multiple data streams. Doing so effectively amplifies the medium's capacity.

There's a catch, however: traditional optical amplification techniques show that as we scale transmission capacity, the power consumption of optical amplifiers--critical for extended-range optical communication--increases proportionally. NTT's theory was that a multicore structure, where multiple cores share the amplifying light, could bring energy savings.

Amplifying optical fiber can directly boost an optical signal as it passes through it, without having to convert it into an electrical signal. NTT adopted a structure consisting of 12 densely packed cores and succeeded in creating increased transmission capacity and energy efficiency within the C-band, the 1530 to 1565 nanometer part of the spectrum used in optical fiber networks for signal transmission. NTT not only worked to maximize the core area ratio within the amplifying optical fiber's cross-section, it also refined the optical amplifier setup, ensuring minimized excitation light loss. Thanks to its two pioneering approaches, it achieved a world's first 67% power reduction compared to conventional methods.

NTT's aim is to finalize this technology by 2030 and use it for spatial division multiplexed transmission paths beyond 10 channels. This aligns perfectly with its IOWN vision.

The IOWN (Innovative Optical and Wireless Network) concept is a vision for a futuristic network and information processing infrastructure. Anchored in technologies that harness the power of light, this infrastructure is designed to deliver high-speed, high-capacity communication and vast computational resources. The primary mission of IOWN is to go beyond the limitations of current infrastructure by leveraging groundbreaking optics-centered technologies.

NTT's vision for the future is clear. Laying the foundations for huge energy savings in optical amplifiers, while at the same time increasing transmission capacity. With breakthroughs such as its work on spatial division multiplexing, it is working to deliver energy-efficient, long-distance, and high-capacity optical amplified transmission. Transmission, moreover, that is in accordance with its environmental strategy, "NTT Green Innovation toward 2040," which emphasizes simultaneous environmental conservation and economic growth.

NTT--Innovating the Future of Communication

Picture: Daniel O'Connor

Daniel O'Connor joined the NTT Group in 1999 when he began work as the Public Relations Manager of NTT Europe. While in London, he liaised with the local press, created the company's intranet site, wrote technical copy for industry magazines and managed exhibition stands from initial design to finished displays.

Later seconded to the headquarters of NTT Communications in Tokyo, he contributed to the company's first-ever winning of global telecoms awards and the digitalisation of internal company information exchange.

Since 2015 Daniel has created content for the Group's Global Leadership Institute, the One NTT Network and is currently working with NTT R&D teams to grow public understanding of the cutting-edge research undertaken by the NTT Group.