Demonstration of 1.44 Tbit/s OAM Multiplexing Transmission in Sub-THz Bands

This paper presents the first experimental demonstration of 1.44 Tbit/s wireless data transmission based on orbital angular momentum (OAM) multiplexing using Butler matrices in sub-terahertz (sub-THz) bands. A Butler matrix is an analog device that performs discrete Fourier transform (DFT) processing and can be combined with a uniform circular array (UCA) for multiplexing OAM waves. We designed and implemented 8×8 Butler matrices with integrated UCAs capable of generating and separating eight OAM waves. The channel response measurements of the developed Butler matrices demonstrated a high level isolation greater than 15 dB in a wide frequency band from 135 GHz to 170 GHz. Experimental results showed with could achieve 1.44 Tbit/s wireless multiplexing transmission at a distance of 1 m using eight OAM modes and dual polarization (16 streams) in the 32-GHz bandwidth.