Tunable metasurfaces enabled by phase-change materials

Recent progress in the miniaturization of optical components was enabled by the emergence of metasurfaces, which allow for manipulation of the amplitude, phase, and polarization of light on length scales smaller than the wavelength. Typically, metasurfaces comprise regularly arranged, subwavelength-sized metallic or dielectric nano-resonators with varying geometry, size, shape, or orientation. Furthermore, they possess effective optical properties resulting from light interaction with the individual nano-antennas leading to unconventional optical responses. Yet, the functionality is limited by the lack of in-operando tunability individual scatterers. Phase-change materials are introduced as active media into metasurfaces to overcome this limitation. The optical and electrical properties of such materials are drastically changed when switching between amorphous and crystalline states. The combination of phase-change materials and metasurfaces allows control over the optical response on demand, which paves the way for dynamically switchable, tunable, and reconfigurable functionalities in active phase-change metasurfaces. © 2024