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.
The company noted that it has now successfully achieved communication over a distance of more than 10 km and communications at different elevations with FSO communication by applying its capture and tracking technology developed for its communication systems and long-distance optical communication technology used in satellites.
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Portability and Quantum Cryptography Integration
Looking ahead, NEC plans to improve communication quality and further reduce the size of the FSO devices, targeting a more portable model by 2028. The company is also exploring the integration of quantum cryptography to enhance security, with the eventual goal of developing free-space quantum key distribution for even more secure communication systems. This technology is expected to play a key role in critical infrastructure and satellite-to-ground communication in the future.
