Nonvolatile Optically Reconfigurable Radiative Metasurface with Visible Tunability for Anticounterfeiting.

Area of Science:

• Metamaterials and Nanophotonics
• Thermal Engineering
• Optical Engineering

Background:

• Controlling thermal emission is crucial for heat and infrared wave transport, but achieving nonvolatile reconfigurability in conventional materials is difficult.
• Existing radiative materials and structures often have inherent complexities or limitations hindering dynamic thermal emission control.

Purpose of the Study:

• To experimentally demonstrate a nonvolatile, optically reconfigurable mid-infrared coding radiative metasurface.
• To explore the potential for dynamic encoding of infrared emissive patterns and visible scattering characteristics.

Main Methods:

• Utilized an ultrathin (∼25 nm) Germanium-Antimony-Tellurium (Ge₂Sb₂Te₅) layer integrated into a planar optical cavity.
• Applied laser pulses to optically crystallize Ge₂Sb₂Te₅ spots, encoding infrared emissive patterns.
• Generated submicron-sized bumps using high-power laser pulses to independently modulate visible scattering patterns.

Main Results:

• Achieved repeated switching of peak spectral emissivity between low (∼0.1) and high (∼0.7) values via optical crystallization.
• Demonstrated independent modulation of visible scattering patterns, creating spatially distinct visual information.
• Successfully created an anticounterfeiting label by encoding unique infrared emission and visible scattering data.

Conclusions:

• This work presents a novel route for advanced thermal emission control using optically reconfigurable metasurfaces.
• The developed technology offers significant potential for applications in anticounterfeiting, encryption, and dynamic camouflage.