Metamaterials (MMs) as three-dimensional (3D) artificial designed periodic subwavelength composite materials/structures can possess extraordinary and unique physics properties not readily available in nature. Metasurfaces (MSs), as a subbranch of the MMs specifically designed subwavelength unit cells in a two-dimensional (2D) plane, offer a new paradigm to design compact and integrated elements that show great potential for miniaturizing photoelectric systems. MSs can exhibit exotic abilities to freely manipulate electromagnetic (EM) waves on a flat and ultrathin platform, and have attracted intensive attention recently resulting in numerous new concepts and novel effects that could find applications in many different aspects including detection and sensing, imaging, data encryption, display, communication, quantum optics and so on. However, most of the current reported MSs only have a single and simple function and usually can only operate in a fixed frequency range, hence the function and performance properties cannot be modulated as desired, which greatly limits their practical applications.

Active control of MSs is highly desired in practical applications, as it adds a further degree of freedom to control EM waves. In principle, tuneable MSs can be realized by adding external optical, electrical, mechanical, thermal, and other stimulation methods. Synthesis, properties, and applications of tuneable MSs have become one of the most relevant branches of modern electromagnetism, optics, and physics. The possibility of managing physical properties through the size, shape, and structure allows for the design of tuneable MSs with a wide range of possible novel photoelectric devices and related applications. However, many fundamental and technical issues regarding the tuneable MSs remain to be solved before such devices can be used in practice. It is, therefore, crucial to develop new synthetic tool design methods that allow for the formation of tuneable MSs suitable for the rational construction of multifunction integrated photoelectric devices.

The aim of this Special Issue is to collate original research and review articles with a focus on recent advances in tuneable MSs by optical, electrical, mechanical, thermal, and other stimulation methods in their synthesis, fabrication, properties, and applications.

Potential topics include but are not limited to the following:

• Graphene metasurfaces
• Si-based metasurfaces
• InSb metasurfaces
• Liquid crystal metasurfaces
• Micro-electromechanical metasurfaces
• Optical metasurfaces
• Terahertz metasurfaces
• Phase-changing metasurfaces
• Thermal metasurfaces
• All-dielectric metasurfaces
• Fabrication technology for metasurfaces