Dual‐Encrypted Chiral Imaging Based on VO 2 Thermal Metasurfaces

ABSTRACT Chiral imaging encryption, which encodes information in meta‐atoms revealed under specific polarization states, is a promising security technology. However, conventional methods rely on external light sources and offer only a single polarization channel, which hinders miniaturization and integration. Herein, we demonstrate an intelligent metasurface based on vanadium dioxide (VO 2 ) phase‐change material (PCM) that overcomes these limitations. The metasurface generates linearly polarized thermal radiation with a linear dichroism (LD) of 0.71 in the insulating VO 2 phase and chiral emission with a circular dichroism (CD) of 0.58 in the metallic VO 2 phase, enabling dynamic switching between polarization states via temperature control. In addition, the LD and CD can be broadly tuned by modifying geometric parameters. Based on this mechanism, we designed a digitally encoded metasurface composed of diverse meta‐atoms, which conceals specific patterns that are only revealed under the proper combination of operating temperature and polarization state, thus achieving image dual‐encryption. Furthermore, the metasurface could display distinct images with low crosstalk under non‐orthogonal polarization states, which stems from the different capabilities of geometric parameters to modulate elliptically polarized radiation. Our work establishes a new paradigm for eco‐friendly optical devices, providing key theoretical and technical support for intelligent thermal radiation modulation.