Nonlinear Exciton‐Mie Coupling in Transition Metal Dichalcogenide Nanoresonators

Thanks to a high refractive index, giant optical anisotropy, and pronounced excitonic response, bulk transition metal dichalcogenides (TMDCs) have recently been discovered to be an ideal foundation for post‐silicon photonics. The inversion symmetry of bulk TMDCs, on the other hand, prevents their use in nonlinear‐optical processes such as second‐harmonic generation (SHG). To overcome this obstacle and broaden the application scope of TMDCs, MoS2 nanodisks are engineered to couple Mie resonances with C‐excitons. As a result, their alliance produces 23‐fold enhancement of SHG intensity with respect to the resonant SHG from a high‐quality exfoliated MoS2 monolayer under C‐exciton excitation. Furthermore, SHG demonstrates a strongly anisotropic response typical of a MoS2 monolayer due to the single‐crystal structure of the fabricated nanodisks, providing a polarization degree of freedom to manipulate SHG. Hence, these results significantly improve the potential of bulk TMDCs enabling an avenue for next‐generation nonlinear photonics.