Electromechanically Reconfigurable Terahertz Stereo Metasurfaces.

Dynamic terahertz devices are vital for the next generation of wireless communication, sensing and non-destructive imaging technologies. Metasurfaces have emerged as a paradigm-shifting platform, offering varied functionalities, miniaturization and simplified fabrication compared to their three-dimensional counterparts. However, the presence of in-plane mirror symmetry and reduced degree of freedom imposes fundamental limitations on achieving advanced chiral response, beamforming, and reconfiguration capabilities. In this work, we demonstrate a platform composed of electrically actuated resonators that can be colossally reconfigured between planar and 3D geometries. To illustrate the platform, metadevices with 3D Split Ring Resonators have been fabricated wherein we combine two counteracting driving forces - (i) folding induced by stress mismatch which enables non-volatile state design, and (ii) unfolding triggered by the strain associated with insulator-to-metal transition in VO 2 , which facilitates volatile structural reconfiguration. This large structural reconfiguration space allows for resonance mode switching, widely tunable magnetic and electric polarizabilities, and increased frequency agility. Moreover, the unique properties of VO 2 such as the hysteretic nature of its phase transition is harnessed to demonstrate a multi-state memory. Therefore, these VO 2 integrated metadevices are highly attractive for the realization of 6G communication devices such as reconfigurable intelligent surfaces, holographic beam formers, and spatial light modulators. This article is protected by copyright. All rights reserved.