Dynamically Controlling Spatial Energy Distribution with a Holographic Metamirror for Adaptive Focusing

Metasurfaces composed of elementary cells with elaborated tailoring of amplitude and phase responses have promising applications for the manipulation of electromagnetic waves. In this work, spatial energy distribution is manipulated to control an incident plane wave and focus it to any desired spatial position. A holographic metamirror implementing proper phase-profile distributions necessary to dynamically control the focal spot is designed. Near-fieldmeasurements are performed on a fabricated prototype to demonstrate energy focusing at predicted focal points. Furthermore, the reconfigurability mechanism implemented in the metasurface allows us to validate an adaptive focusing by modifying both the number and the position of the focal spots through the electronic tuning of the phase profile. Such a spatial energy manipulation concept paves the way to flat and efficient devices for wireless-power-transfer applications in the radio-frequency domain as well as for imaging and holography functionalities at much higher frequencies.