Tunable GST metasurfaces for chromatic aberration compensation in the mid-infrared

Metasurfaces for chromatic aberration compensation have attracted a lot of research attentions since almost all imaging systems suffer from the intrinsic dispersion of composite materials and the chromatic aberration. However, most of them rely on complicated optimization of the structural parameters, hindering their practical application. Here we proposed a new and simple scheme of metasurface for chromatic aberration compensation based on phase change materials. As a demonstration, Ge2Sb2Te5(GST) is used to design metalens and deflector with reduced chromatic aberration that works over a broad band of wavelengths. Simulation results show that we can simply reduce the chromatic aberration fromλ = 8μm to λ = 9μm via uniformly tuning the crystalline fraction of GST. In addition, we demonstrate that the working wavelength can be extended to a wider range fromλ = 8μm to λ = 11μm via individually engineering the crystalline fraction of each GST cylinder. Our metadevice serves as a novel paradigm for mid-infrared devices with compensated chromatic aberration, enabling a wide variety of application.