Graphene-enabled dynamic metasurfaces and metadevices

Fig.1 Overview of state-of-the-art selected functionalities of dynamic metasurfaces and metadevices empowered by graphene. Credit: Compuscript Ltd

A new article in Opto-Electronic Advances discusses graphene-enabled dynamic metasurfaces and metadevices.

Metasurfaces, which are artificial subwavelength structured interfaces, have hitherto unmatched capabilities for manipulating electromagnetic (EM) waves ranging from visible to terahertz and microwave frequencies.

The static metasurfaces and metadevices have been actively investigated throughout the last decade. However, due to the passive nature of building blocks consisting of metals and/or dielectrics, their functions cannot be actively tweaked in situ following manufacturing, severely limiting potential application scenarios such as varifocal lenses, dynamic holography, and LiDAR beam steering. Motivated by these substantial needs, scientists have been battling for years to improve the dynamical tunability of metasurfaces, with the first concept being to incorporate active materials or components into passive metasurfaces.

Various active materials and components, such as transparent conducting oxides, phase-change materials, two-dimensional materials (particularly graphene), varactor diodes, elastic materials, and micro-electro-mechanical systems, have been demonstrated theoretically and experimentally to enable active tunability of metasurfaces and metadevices via external thermal, electrical, optical, and mechanical stimulus, thereby establishing a new direction, namely, dynamic (e.g.

It should be noted that, while prior research serves as a significant source of inspiration for dynamic metasurfaces and metadevices, each type of active material and component possesses a unique set of characteristics, presents exciting opportunities, and also presents unique limitations and challenges. Numerous review articles have been written in recent years that explore the aforementioned topics. However, a complete evaluation of graphene-based dynamic metasurfaces and metadevices is still lacking, despite their importance being comparable to or greater than that of graphene’s exceptional capabilities.

The authors divide graphene-enabled dynamic metasurfaces and metadevices into two categories in this study, namely metasurfaces with structured graphene building blocks and hybrid metasurfaces integrated with graphene, as illustrated in Fig. 1. The state-of-the-art advances in dynamic spectrum manipulation, wavefront shaping, polarization control, and frequency conversion are extensively discussed in terms of near/far fields and global/local interactions. Additionally, remaining obstacles and prospective future advancements are discussed and examined.

The authors believe that due to their inherent advantages of small footprint, remarkable electrical tunability, broad bandwidth, and high-speed operation, graphene and graphene-like 2D materials are catapulting EM wave manipulations using metasurfaces to a new level: from static to dynamic, which will undoubtedly revolutionize EM wave manipulations and enable future commercial applications.

Further information: Chao Zeng et al, Graphene-empowered dynamic metasurfaces and metadevices, Opto-Electronic Advances (2022). DOI: 10.29026/oea.2022.200098

Source: Compuscript Ltd