A THz-OAM Wireless Communication System Based on Transmissive Metasurface

With the development of various emerging technologies, the capacity of current wireless communication system is gradually saturated, and terahertz (THz) and orbital angular momentum (OAM) have hereby attracted much attention as two key technologies to increase the communication capacity. In this article, a THz-OAM wireless communication system operating at 100 GHz based on a transmissive metasurface is proposed for the first time to the best of our knowledge. The operation principle of multiplexing metasurface, which allows simultaneous generation of two coaxial OAM beams at different modes of $\boldsymbol {l}$ = 1 and −1, is studied. To meet the requirements of wireless communication and OAM multiplexing, a C-shaped transmissive unit is designed with characteristics of broad bandwidth, low transmission loss, and insensitive to the change of incident angle. Experimental measurements show that the generated two OAM beams feature high mode purity, providing the excellent orthogonality of modes. The generated two OAM modes are also employed as two OAM channels to transmit two independent communication signals with ON–OFF keying (OOK) modulation, and a data rate of 10 Gbit/s is achieved at a transmission distance of 300 mm ( $100\boldsymbol {\lambda }$ of 100 GHz) with bit error rates (BERs) below $3.8\,\,\boldsymbol {\times }\,\,\boldsymbol {10^{-3}}$ . This work verifies the feasibility of the multiplexing metasurface supporting wireless communication and makes THz-OAM wireless communication systems potential for future large capacity wireless services.