NEC Corporation (NEC) has successfully achieved Japan’s longest terrestrial wireless optical communication, or free-space optical (FSO) communication, over a distance of more than 10 kilometers.
FSO communication is a method that facilitates high-speed, high-capacity communication, surpassing traditional radio waves. It works by transmitting and receiving light beams without the need for physical paths like optical fibers. FSO has high directionality, meaning it doesn’t spread beams, reducing the risk of interception by third parties and minimizing interference and congestion in communication.
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From January to February 2025, NEC conducted a communication demonstration between a pair of FSO communication devices located more than 10 kilometers apart in Nasushiobara City, Tochigi Prefecture. As a result, NEC confirmed that automatic capture and tracking of bidirectional optical beams functioned correctly even over long distances, enabling communication.
Building on this in March 2025, NEC conducted a demonstration of FSO communication between the rooftop of a TOKYO SKYTREE observation deck, which is 350 meters above ground level, and a point on the ground approximately 3 kilometers away. As a result, NEC confirmed that communication was possible and also measured the effects on communications from atmospheric turbulence due to elevation differences.
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NEC will advance technological development based on the success of this demonstration to improve communication quality and reduce the device size from approximately 2 m³ to about 1% of the current size, so that it can be carried by one person, with plans to commercialize it by 2028.
Furthermore, by combining quantum cryptography communication technology—which is expected to be applied to national-level critical infrastructure systems—with FSO communication technology, NEC aims to develop free-space quantum key distribution (QKD) technology in the future, thereby enabling more secure communication. NEC also aims to apply this technology to communications between ground and satellites while continuing to advance its efforts in providing networks tailored to the diverse needs of its customers.
