Engineering Thermal Emission with Enhanced Emissivity and Quality Factor Using Bound States in the Continuum and Electromagnetically Induced Absorption

Abstract Metal‐based thermal metasurfaces exhibit stable spectral characteristics under temperature fluctuations, in contrast to more traditional gray‐ and near black‐bodies, as well as some dielectric metasurfaces, whose emission spectra shift with changing temperatures. However, they often suffer from limited quality (Q) factors due to significant non‐radiative ohmic losses. This study addresses the challenge of achieving high emissivity and Q‐factors in metal‐based thermal emitters. By leveraging the coupling of three surface lattice resonances that support bound states in the continuum and electromagnetically induced absorption (EIA), this work designs a metal‐based thermal metasurface with a near‐unity emissivity (0.96) and a Q factor as high as 320 through simulations. Experimental validation yields an emissivity of 0.82 and a Q factor of 202, representing an approximately fivefold improvement in the experimentally measured Q factor compared to the state‐of‐the‐art metal‐based thermal metasurfaces. This work offers a promising approach for developing efficient, narrow‐band, directional thermal emitters with stable emission spectra across a wide temperature range.