Abstract
Triggered by the development of exfoliation and the identification of a wide
range of extraordinary physical properties in self-standing films consisting of
one or few atomic layers, two-dimensional (2D) materials such as graphene,
transition metal dichalcogenides (TMDs), and other van der Waals (vdW) crystals
currently constitute a wide research field protruding in multiple directions in
combination with layer stacking and twisting, nanofabrication, surface-science
methods, and integration into nanostructured environments. Photonics
encompasses a multidisciplinary collection of those directions, where 2D
materials contribute with polaritons of unique characteristics such as strong
spatial confinement, large optical-field enhancement, long lifetimes, high
sensitivity to external stimuli (e.g., electric and magnetic fields, heating,
and strain), a broad spectral range from the far infrared to the ultraviolet,
and hybridization with spin and momentum textures of electronic band
structures. The explosion of photonics with 2D materials as a vibrant research
area is producing breakthroughs, including the discovery and design of new
materials and metasurfaces with unprecedented properties as well as
applications in integrated photonics, light emission, optical sensing, and
exciting prospects for applications in quantum information, and nanoscale
thermal transport. This Roadmap summarizes the state of the art in the field,
identifies challenges and opportunities, and discusses future goals and how to
meet them through a wide collection of topical sections prepared by leading
practitioners.