Adaptive radiative cooling by Fabry-Perot resonators with ultra-thin surface: A theoretical study

The ultra-thin interface exhibits distinct optical and electrical properties diverging from the bulk medium. Thinning the metallic layer of a Fabry-Pérot cavity enables spectral broadening of bound states in the continuum (BICs) within the atmospheric window, thus facilitating its application in radiative cooling.The design of a step metasurface further broadens the emissivity peak to meet the required cooling power specifications. Vanadium dioxide (VO₂) integration adds adaptive temperature responsiveness, forming four distinct unit cell configurations active within both the atmospheric window and solar spectrum. The temperature responses of these four unit cells are distinguished through detailed analysis of their absorption properties across these bands, while the impact of structural periodicity is elucidated via absorption medium considerations. Notably, the “MIV_top structure” demonstrates a significant reduction in solar band absorption within the resonant cavity. This work advances the design of adaptive radiative coolers, specifically enhancing their response within the visible spectrum.