Reconfigurable and Polarization‐Dependent Grating Absorber for Large‐Area Emissivity Control Based on the Plasmonic Phase‐Change Material In3SbTe2

Abstract Metasurfaces with perfect infrared absorption promise integrated filters and compact detector elements with narrowband thermal emission. Phase‐change materials (PCMs) are prime candidates for active, non‐volatile absorption tuning. Commonly, the response of the entire metasurface is tuned, while local adaptions remain elusive. In this work, flexible encoding of different absorption/emission properties within a metasurface is shown. The plasmonic PCM In 3 SbTe 2 (IST) is employed to obtain control over the emissivity by patterning an adaptable grating absorber metasurface. Using a commercial direct laser writing setup, the IST is locally switched from an amorphous dielectric into a crystalline metallic state, and cm‐sized stripe gratings are written above a reflecting mirror. Modification of already written patterns is demonstrated by changing the laser power and thus the IST stripe width to encode different polarization‐sensitive patterns with nearly perfect absorption into the same metasurface. Finally, an apparent local temperature pattern due to the large‐area emissivity shaping metasurface is measured with a conventional thermal camera. The results pave the way towards low‐cost, large‐area, and adaptable patterning of metasurfaces with wavelength and polarization‐selective perfect absorption, enabling applications like enhanced thermal detection, infrared camouflage, or encoding anti‐counterfeiting symbols.