Broadband Metasurfaces with Simultaneous Control of Phase and Amplitude

Metasurfaces have attracted large interest in recent years due to their relatively simple fabrication, compact design, and ability to control the wavefront of incident light. Ohmic loss attributed to bulk metal metamaterials are not a primary issue, whereby the meta-atom or plasmonic structure is typically only as thin as a fraction of the operation wavelength. Numerous novel applications have been demonstrated by metasurfaces, including an ultrathin metasurface flat lens, and 3D holography. Here, by combining the freedom of both the structural design and the orientation of split ring resonator antennas, we demonstrate Terahertz metasurfaces that are capable of controlling both the phase and amplitude profiles over a very broad bandwidth at ~1THz under linearly-polarised incidence. As an example, we show that these phase-amplitude metasurfaces can be engineered to control the diffraction orders arbitrarily