Multifunctional Spatial Mode Multiplexers Based on All-Dielectric Metasurfaces Working at Terahertz Frequencies

Mode division multiplexing (MDM) is a promising technique for improving data transmission rates in the booming terahertz communication realm. Mode converter and multiplexer play an important role in MDM systems. Here, the silicon based spatial mode multiplexer is proposed to convert the fundamental Gaussian modes to HG 10 mode and HG 11 mode according to the incident polarizations, respectively. By superposing the phase distribution of a meta-lens and a deflector, the converted modes realize designable focusing function as well. The results may inspire multiplexer R&D and promote terahertz communication.