NEC Achieves Over 10 km of Long-Distance Free-Space Optical Communication in Japan

NEC Corporation has achieved what it calls Japan’s longest terrestrial wireless optical communication, or free-space optical (FSO) communication, over a distance of more than 10 km. According to the Japanese company, the demonstration marks a significant advancement in the FSO technology, offering high-speed, high-capacity wireless communication without the need for physical fiber optics.

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Tokyo Skytree Demonstration

In addition, NEC conducted an FSO communication test between the observation deck of the Tokyo Skytree, located 350 meters above ground level, and a ground station 3 kilometres away. This demonstration, conducted in March 2025, confirmed the viability of FSO communication across varying elevations while also measuring the impact of atmospheric turbulence on signal stability, according to NEC.

FSO Communication Benefits

FSO communication transmits data via light beams, offering several advantages over traditional radio wave-based methods, including reduced interference, a lower risk of interception, and no requirement for radio wave usage permits. It is particularly beneficial in areas where installing optical fiber is difficult—such as remote regions or during disaster recovery when conventional communication networks are disrupted.

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Future Applications

NEC stated that these newly developed technologies are expected to be used in locations where optical fiber installation is challenging, as well as for communication between ships at sea and onshore stations. Additionally, they may serve as an alternative or emergency communication method in disaster scenarios when wired networks are damaged, and for secure short- and medium-range communications related to national security.