Tunable, reconfigurable, and programmable metamaterials

Electromagnetic metamaterials have been developing rapidly and attracted worldwide attentions since the concept has been proposed due to their powerful ability in controlling electromagnetic (EM) waves. Active functions and features achieved by tunable or reconfigurable metamaterials are highly desired in the field of science, engineering, and military. With the introduction of digital metamaterials, a bridge between the physical world and the information world is set up. When the digital metamaterials are programmable, they enable the wave-based information coding and processing on the physical level of metamaterials in real time. In this paper, we will summarize the recent progress on tunable, reconfigurable, and programmable metamaterials. Firstly, we introduce the tunable and reconfigurable metamaterials in terahertz and microwave frequencies. Secondly, we review the functional devices and novel systems by the programmable metamaterials. Finally, we give a brief developing prospect to the programmable metamaterials.