Broadband Terahertz Achromatic Metasurface with Linear Spatial Phase Gradients

We demonstrated three kinds of broadband terahertz achromatic metasurfaces with linear phase gradients including a deflector, a beam splitter and an axicon, whose phase and dispersion were simultaneously engineered by changing the geometric parameters of the unit cells. The devices presented here may inspire novel achromatic metasurfaces and promote the development of broadband terahertz devices.