Terahertz programmable metasurface based on free carrier plasma dispersion effect

🔗 Paper Link

Summary

Terahertz modulators hold great promise for applications in terahertz intelligent communication and computational imaging, among other fields. However, existing terahertz phase modulators fail to meet expectations in terms of speed, efficiency, and flux. Therefore, there is an urgent need to develop high-speed, high-efficiency, and high-flux terahertz spatial light modulators.

We proposed a design for a terahertz programmable metasurface based on the free carrier plasma dispersion effect. By integrating PN junctions into the “H”-shaped metallic metasurface unit structure. We utilized the change in the carrier concentration distribution of the PN junctions induced by the application of an external voltage. Simulations have demonstrated continuous phase modulation of 270° at a frequency of 0.4 THz and an average efficiency of 30%. The metasurface unit employs an “MIM” structure, with each unit being independently adjustable. Moreover, it leverages the high-speed switching characteristics of the PN junction, which is expected to achieve modulation speeds up to the GHz level. The team also demonstrated the far-field radiation pattern of the metasurface unit array, with a peak side-lobe ratio of 13 dB, indicating good beam steering performance.