Plasmonic-excitonic nonlinear metasurface engineered from toroidal plasmons and 2D-MoSe

Two-dimensional transition metal dichalcogenides (TMDCs) are materials of extreme interest for the development of nonlinear optoelectronic devices due to their atomic thickness and strong optical nonlinearities. We integrated a plasmonic metasurface device with the TMDC 2D- MoSe₂ to achieve enhancement of higher-order generation mediated by the nanostructures and study the hybridization of toroidal plasmons and 2D excitons within this system. To engineer this integrated platform, we designed a metasurface consisting of arrays of gold nanoresonators with a toroidal dipole magnetic moment and lithographically patterned this metasurface atop monolayer MoSe₂ using e-beam lithography. Optical reflectivity and harmonic generation measurements show enhanced linear and nonlinear interactions of this hybrid metasurface.