Focused thermal emission from radiative metasurface

In the field of mid-infrared (m-IR) applications, there is a need to control thermal radiation from metal-insulator-metal (MIM) metasurfaces without any optical components. Here, we introduce the concept of metalens for the MIM metasurfaces. The finite difference time domain (FDTD) simulation was used to design the radiative metasurface to focus its thermal radiation. The electron beam lithography was then implemented to define a 5-mm-diameter radiative metalens. Its focusing performance is experimentally validated by direct measurement of the spatial distribution of the thermal radiation.