Fig. 1. (a) Hemispherical scattering distribution model under external heat source conditions. (b) Schematic diagram of dynamic emissivity modulation. (c) Schematic illustration of the SETTE, consisting of a scattering substrate, 800 nm Ag, and 450 nm GST. (e) SEM image of the substrate. (f) SEM image of the fabricated SETTE device. (g) Measured reflectivity spectra at normal incidence for SETTE devices in aGST, FCC-GST, and HEX-GST phases. (h) and (i) Distribution of the electric field for aGST and HEX-GST under 10.6 μm at an incidence angle of 45°.

Fig. 2. IR images and radiance spectra of the object and the background. (a) Schematic image of the experimental setup. The system comprises two heating stages: one is used to anneal the background (blackbody) at temperatures varying from 35°C to 45°C, while the other is employed to maintain the target (SETTE device) at a fixed temperature of 50°C. (b)–(e) IR images captured by the IR camera at different background temperatures (35°C and 45°C), with the target (SETTE device) held at 50°C in aGST and HEX-GST phases. (f) Measured average emissivity (7.5–13 μm) of aGST under different heating durations and temperatures. (g) Comparison of the average emitted power (7.5–13 μm) among the background, aGST, and HEX-GST phases of the SETTE device at various temperatures.

Fig. 3. Thermal performance and IR image of the SETTE device under varying temperatures and external heat source conditions. (a) Schematic of the experimental setup. The system comprises three heating platforms: one maintains the background (blackbody) at 45°C, another fixes the target (SETTE) at 50°C or 70°C, and a third simulates an external heat source at 100°C placed at 45°, with the IR camera positioned at the corresponding specular reflection angle. (b) IR images with an external heat source: comparison between 50°C low-e surface and aGST, and 70°C low-e surface and HEX-GST. (c) IR images under the presence of the external heat source, similarly contrasting the 50°C low-e surface and aGST, and the 70°C low-e surface and HEX-GST. (d) Comparison of the average emitted power (7.5–13 μm) of the background, aGST-based SETTE, and HEX-GST-based SETTE at various temperatures under the presence of the external heat source. (e) and (f) Contributions of thermal radiation (yellow) and reflection of the external heat source (green) for the SETTE in the aGST and HEX-GST, respectively.

Fig. 4. Robustness of the SETTE thermal camouflage to varying observation angles. (a) and (b) Infrared images of aGST and HEX-GST recorded by the infrared camera at observation angles ranging from 20° to 60°. The background temperature is 35°C in (a) and 45°C in (b), while the target temperature remains at 50°C in both cases. (c) Measured directional emissivity of aGST from 0° to 70°. (d) Measured directional emissivity of HEX-GST from 0° to 70°. (e) Measured specular reflectance of aGST and HEX-GST over incidence angles from 15° to 60°.