Dynamic modulation of terahertz photonic orbital angular momentum superposition states based on vanadium dioxide metasurface

Abstract

The combined state of photonic orbital angular momentum (OAM) offers more degrees of freedom compared to an OAM state, revealing rich physical implications and significant engineering potential. In this paper, we propose a dynamic control scheme employing a VO₂ metasurface to generate two polarization-dependent OAM channels, enabling multiplexed terahertz OAM superposition states. This design doubles channel capacity and supports dynamic switching between superposition and single OAM states via VO₂ phase transitions. We designed and simulated two types of OAM-superposition metasurface generators. The first design features a VO₂-Au hybrid array structure, capable of flexibly switching between various OAM superposition states and a single OAM state. The second design consisted of a metasurface array composed of VO₂ units, allowing for dynamic control over the activation and deactivation of multiple OAM superposition states. Furthermore, the proposed metasurfaces enable the generation of longitudinal electric field components and the dynamic control of OAM superposition states. The proposed scheme employs a single metasurface to achieve multifunctional dynamic control, and offers a novel approach and methodology for photonic OAM manipulation.