Terahertz full-space metasurface based on thermally induced phase transition: dynamic wavefront manipulation and multifunctional applications

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Abstract Dynamic manipulation of electromagnetic (EM) waves with multiple degrees of freedom remains a significant challenge in the field of electromagnetic control. To address the requirements for multifunctionality and tunability of metasurfaces, this paper proposes a full-space terahertz wavefront dynamic control structure based on a thermally induced phase transition metasurface. The metasurface is composed of high-refractive-index silicon nanocolumns, a polytetrafluoroethylene (PTFE) dielectric layer, and a vanadium dioxide (V O 2 ) thin film with reversible phase transition characteristics. Through precise design of the unit geometric structure, independent wavefront manipulation in reflection and transmission modes is achieved. Simulation results show that the metasurface exhibits a transmission amplitude greater than 0.8 in the 1.45–1.59 THz frequency band and a reflection amplitude exceeding 0.8 in the 0.85–1.29 THz band, demonstrating the superior performance of the metasurface unit structure. By combining the Gerchberg-Saxton algorithm, this study realizes full-space orbital angular momentum (OAM) beam generation and high-quality holographic image reconstruction. Furthermore, the metasurface is successfully applied to encrypted communication, enhancing information security. This work presents a thermally reconfigurable metasurface platform that enables independent full-space wavefront control in both reflection and transmission modes, a capability not achieved simultaneously in previous studies. Unlike existing designs that typically operate in a single mode or lack dynamic tunability, our approach integrates V O 2 -based thermal phase transition with H-shaped silicon nanocolumns, achieving bidirectional OAM generation, high-quality holographic imaging, and multi-channel encryption within a single compact structure. This new multifunctional solution offers significant advances in terahertz wave manipulation and opens up possibilities for secure, reconfigurable THz photonics in various applications.

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