In the field of mid‐infrared (m‐IR) applications, a need exists to control thermal radiation from metal‐insulator‐metal (MIM) metasurfaces without any additional optical components. Here, we introduce the metalens concept for radiation control from MIM metasurfaces. A finite‐difference time‐domain (FDTD) simulation is used to design the radiative metasurface to focus its thermal radiation. Electron‐beam lithography is implemented to fabricate a 5‐mm‐diameter radiative metalens. Experiments to measure the thermal radiation from metasurfaces validate the focusing performance of the metalens by direct measurement of the 3D spatial distribution of thermal radiation. These findings form the basis for engineering metasurfaces for focusing thermal radiation and can be applied in areas such as gas sensor design, semiconductor device cooling, and energy harvesting.
Kawaida et al. (Sun,) studied this question.