Successful Terahertz Wireless Communication Using A Micro-Resonator Soliton Comb: Expectations For Next-Generation Mobile Communications Based On Photonic Technology

Mobile communications have achieved higher speeds and larger capacities using higher wireless carrier frequencies. Thus far, wireless electronics have been used to generate wireless carriers in mobile communications, but next-generation mobile communications (6G) (Note 1), which are scheduled to start service in 2030, will use terahertz waves of 300 GHz or higher, and may reach the technical limit of wireless electronics (namely, upper limit of frequency for wireless electronics).

The research group comprising Associate Profs. Yu Tokizane, Naoya Kuse, Hiroki Kishikawa, and Prof. Takeshi Yasui of Institute of Post-LED Photonics, Tokushima University; former Assistant Prof. Yasuhiro Okamura of the Graduate School of Technology, Industrial and Social Sciences, Tokushima University; Prof. Shintaro Hisatake of the School of Engineering, Gifu University; and Prof. Atsushi Kanno of the National Institute of Information and Communications Technology (NICT) and the Department of Engineering, Nagoya Institute of Technology generated terahertz waves using a micro-resonator soliton comb (Note 2) and applied them to wireless communication at 560-GHz band to solve the described problems. The focus of this study was on the feature that optical frequency spacing of the micro-resonator soliton comb was equivalent to the 6G carrier frequency, and this was used as an ultra-high-frequency photonic RF signal in optical-to-electrical conversion to generate terahertz waves as part of a wireless communication system. This method is expected to not only overcome the technical limit of wireless electronics but also achieve 6G with ultra-high speed and large capacity through advanced modulation and demodulation of amplitude and phase, and which has high affinity with optical communication.

Terminology
(Note 1) Next-generation mobile communication (6G)
Next-generation mobile communications (6th-generation mobile communications) that are scheduled to start service in 2023 will use terahertz waves of 300 GHz or higher as wireless carriers. The communication methods require conditions such as “Extreme high data rate/capacity,” “Extreme low latency,” “Extreme coverage,” “Extreme high reliability,” “Extreme low energy and cost,” and “Extremely massive connectivity and sensing.”

(Note 2) Micro-resonator soliton comb
A micro-resonator soliton comb has an ultra-discrete multispectral structure in which multiple optical frequency modes are arranged at regular spacings similar to a hair comb, and it is possible to generate ultra-high-frequency photonic RF signals that are of immensely higher quality than those generated by electrical methods. Furthermore, because semiconductor processes can be used for mass-production, micro-resonator soliton combs can be expected to be ultra-compact, simple, and low-priced in the future