Strong Light–Matter Interactions Enabled by Polaritons in Atomically Thin Materials

Abstract

Polaritons, resulting from the hybridization of light with polarization charges formed at the boundaries between media with positive and negative dielectric response functions, can focus light into regions much smaller than its associated free‐space wavelength. This property is paramount for a plethora of applications in nanophotonics, ranging from biological sensing to photocatalysis to nonlinear and quantum optics. In the two‐dimensional (2D) limit, represented by atomically thin and van der Waals (vdW) materials of single‐layers bound by weak vdW attraction, polaritons are characterized by extremely small wavelengths associated with extreme optical confinement, and furthermore can exhibit long lifetimes, electrical tunability, and extreme sensitivity to their dielectric environment, among many other desirable qualities in nano‐optical device applications. Here, the fundamentals of polaritons in atomically thin materials are summarized, emphasizing plasmon and exciton polaritons, their strong light–matter interactions, and nonlinear plasmonics. More specifically, this review opens with a pedagogical discussion of plasmons in extended and nanostructured graphene, providing a classical electrodynamical model in a nonretarded theoretical framework, and the ultraconfined acoustic plasmons supported by hybrid graphene–dielectric–metal structures. In addition, the basic principles are introduced and the recent developments on nonlinear graphene plasmonics and on strong coupling physics with atomically thin transition metal dichalcogenides are reviewed. Finally, potentially new, promising research directions in the burgeoning field of 2D nanophotonics are identified.

Stimulated plasmon polariton scattering

“…We consider two possible placements of the graphene: either as a narrow ribbon inside the waveguide gap for maximal field enhancement or placed on top of the waveguide as a more practical arrangement. We note that the dispersion relation of such ribbons differs from that of infinitely extended graphene due to the lateral confinement 34 . In our example system, the second-order nonlinearity stems entirely from the intrinsic ponderomotive force of the electron system in graphene.…”

A Review on the Development of Tunable Graphene Nanoantennas for Terahertz Optoelectronic and Plasmonic Applications

“…Vortex beams have attract a great deal of interest in previous years on account of promising examinations, guaranteeing that OAM may give improved transmission characteristics compared to some other communication technologies [235,236]. Although OAM multiplexing is a subset of MIMO devices and consequently has less gain capacity than MIMO devices [237], vortex beams have stimulating utilization in the field of communication with improved encryption abilities, laser detection and optical energy trapping [238]. However, the formation of such beams is demanding.…”

“…Moreover, graphene patches are a superbly suitable platform for the generation of vortex beams, along with more considerable design adaptability. and consequently has less gain capacity than MIMO devices [237], vortex beams have stimulating utilization in the field of communication with improved encryption abilities, laser detection and optical energy trapping [238]. However, the formation of such beams is demanding.…”

2D materials integrated with metallic nanostructures: fundamentals and optoelectronic applications

“…The polaritonic waves, that is, plasmon polaritons [50], phonon polaritons [51,52], and hybrid exciton polaritons [53][54][55][56], are characterized by extremely small polaritonic wavelength associated with strong optical confinement, giving rise to strong light-matter interactions. For more details, there are a few review articles discussing 2D polaritons [42,43,57]. However, most 2D polaritons exist at the midinfrared window, thus resulting in the challenge to be exploited for the optoelectronic applications in the visible or near-infrared window.…”