Ultrafast reprogrammable multifunctional vanadium-dioxide-assisted metasurface for dynamic THz wavefront engineering

TL;DR

This paper introduces an ultrafast, reprogrammable VO2-based metasurface capable of dynamic THz wavefront manipulation, enabling multiple functions like vortex beam generation and wave focusing with rapid switching for advanced wireless communication.

Contribution

The work presents the first VO2-based coding metasurface with multi-state reprogrammability for dynamic THz wavefront engineering, controlled by bias voltage and FPGA.

Findings

Successfully generated vortex beams with different OAM modes.

Achieved dynamic focusing of THz waves at different points.

Demonstrated ultrafast switching between multiple functionalities.

Abstract

In this paper, for the first time, a new generation of ultrafast reprogrammable multi-mission bias encoded metasurface is proposed for dynamic THz wavefront engineering by employing VO2 reversible and fast monoclinic to tetragonal phase transition. The multi-functionality of our designed VO2 based coding metasurface (VBCM) was guaranteed by elaborately designed meta-atom comprising three-patterned VO2 thin films whose operational statuses can be dynamically tuned among four states of "00"- "11" by merely changing the biasing voltage controlled by an external FPGA platform. Capitalizing on such meta-atom design and by driving VBCM with different spiral-like and spiral-parabola-like coding sequences, single vortex beam and focused vortex beam with interchangeable OAM modes were satisfactorily generated respectively. Additionally, by adopting superposition theorem and convolution operation, symmetric/asymmetric multiple beams and arbitrarily-oriented multiple vortex beams in pre-demined directions with different topological charges are realized. The versatility of our designed VBCM also has equipped a platform to focus the incident THz wavefront into a pre-determined point which can be dynamically altered. Several illustrative examples successfully have clarified that proposed VBCM is a promising candidate for solving crucial THz challenges such as high data rate wireless communication where ultrafast switching between several missions is required.