Implementing Terahertz Spatial Multiplexing and Frequency Demultiplexing Systems Using Diffractive Optical Elements for 6G Telecommunications Applications

As the demand for increased data throughput continues to grow, the bandwidth of current telecommunication networks is reaching its upper limits. This trend highlights the need to deploy new and advanced technologies to expand network capabilities. To address this, future technologies like 6G telecommunication systems aim to incorporate higher terahertz (THz) frequency bands into wireless telecommunication. Thus, research into solutions that enable THz frequencies in telecommunication applications is essential. In this study, the authors present a system for spatial multiplexing and demultiplexing of THz signals in a free space, implemented using three diffractive optical elements (DOEs). This setup achieves spatial separation of signals differing by only 0.9 GHz, which is challenging at frequencies below 100 GHz. This article provides a comprehensive description of the components of the system, covering the design methodologies, innovative spatial modeling techniques, material selection, and manufacturing methods used. Experimental results reveal the progressive evolution of signals within the setup, achieving a clear spatial separation between signals at 95.3 and 96.2 GHz. These findings are vital for the advancement of THz telecommunications, including future 6G systems. Similar approaches could find applications in THz multiple-input multiple-output (MIMO) systems.