Metasurface Spatial Processor for Electromagnetic Remote Control

We introduce the concept of metasurface spatial processor, whose transmission is remotely and coherently controlled by the superposition of an incident wave and a control wave through the metasurface. The conceptual operation of this device is analogous to both that of a transistor and a Mach-Zehnder interferometer, while offering much more diversity in terms of electromagnetic transformations. We demonstrate two metasurfaces, that perform the operation of electromagnetic switching and amplification.