On-chip dynamic manipulation of terahertz spoof surface wavefronts with reconfigurable metasurfaces

The manipulation of spoof surface waves (SSWs) plays a very critical role in terahertz photonics and imaging due to their unique properties. However, the dynamic manipulation of SSW wavefronts remains a major challenge, restricting their wide-ranging applications. Here, we propose an approach to design reconfigurable on-chip metadevices that enable terahertz SSW excitation, wavefront reshaping, and dynamic manipulation in a controllable manner simultaneously. The metadevices consist of two parts: a central active metacoupler composed of VO2-based and VO2-integrated meta-atoms that excite SSWs, and two-sided plasmonic metals that support the on-chip propagation of SSWs. Utilizing the phase transition of VO2, the metacoupler can dynamically reconfigure 2D phase profiles and manipulate the SSW wavefronts. To prove the approach, three types of metadevices are constructed with the above hybrid meta-atoms and plasmonic metals. By altering the working state of VO2, dynamic modulation of spoof surface focusing beams (SSFBs), dynamic switching between SSFBs and spoof surface Bessel beams (SSBBs), and dynamic reconfiguration of spoof surface Airy beams (SSABs) can be achieved, respectively. Therefore, such a strategy opens a new avenue for on-chip dynamic manipulation of terahertz SSW wavefronts, which shows potential applications in integrated terahertz photonic devices and systems.