Graphene-empowered dynamic metasurfaces and metadevices

Metasurfaces, with extremely exotic capabilities to manipulate electromagnetic (EM) waves, have derived a plethora of advanced metadevices with intriguing functionalities. Tremendous endeavors have been mainly devoted to the static metasurfaces and metadevices, where the functionalities cannot be actively tuned in situ post-fabrication. Due to the intrinsic advantage of active tunability by external stimulus, graphene has been successively demonstrated as a favorable candidate to empower metasurfaces with remarkably dynamic tunability, and their recent advances are propelling the EM wave manipulations to a new height: from static to dynamic. Here, we review the recent progress on dynamic metasurfaces and metadevices enabled by graphene with the focus on electrically-controlled dynamic manipulation of the EM waves covering the mid-infrared, terahertz, and microwave regimes. The fundamentals of graphene, including basic material properties and plasmons, are first discussed. Then, graphene-empowered dynamic metasurfaces and metadevices are divided into two categories, i.e., metasurfaces with building blocks of structured graphene and hybrid metasurfaces integrated with graphene, and their recent advances in dynamic spectrum manipulation, wavefront shaping, polarization control, and frequency conversion in near/far fields and global/local ways are elaborated. In the end, we summarize the progress, outline the remaining challenges, and prospect the potential future developments.