Wavelength‐Selective Emission of Ge ₂ Sb ₂ Te ₅ /Si Multilayer Structures for Dynamic Adaptive Camouflage and Optical Security

Abstract Multispectral stealth and optical anti‐counterfeiting technologies are of significant importance in the fields of military defense and information security. The concealment of targets or information is gradually shifting from passive to active, calling for not only multispectral compatibility but also tunable optical properties. Herein, a Ge ₂ Sb ₂ Te ₅ (GST)/Si multilayer metasurface with wavelength‐selective emission is proposed, consisting of a color control module (Si _top ) and an emission control module ([GST/Si] photonic crystal). The visible optical response is determined by the thickness of the top infrared‐transparent layer. Infrared emission is modulated by the phase transition of the embedded GST layer, achieving high emissivity before the phase change and ultra‐low emissivity (0.098) afterward. Furthermore, by adjusting the substrate, the infrared signal can be flexibly tuned, enabling the customization of both color and thermal patterns within a single structure. This design offers a promising solution for adaptive camouflage, information security, and large‐scale manufacturing.