Graphene surface plasmon induced optical field confinement and lasing enhancement in ZnO whispering-gallery microcavity.

Fundamental physics under the surface plasmon (SP) of graphene and the functional application beyond ultraviolet (UV) lasing of ZnO are both fascinating research areas. Herein, the optical field confinement induced by graphene SP was simulated theoretically in a graphene-coated ZnO microrod, which acted as a whispering-gallery microcavity for lasing resonance. Distinct optical field confinement and photoluminescence (PL) enhancement were observed experimentally. Stable and transient spectra were employed to analyze the PL enhancement and the coupling dynamics between graphene SP and ZnO interband emission. As a functional application, the graphene-coated ZnO microcavities presented the obviously improved whispering-gallery mode (WGM) lasing performance. These results would be valuable for designing novel optical and photoelectronic devices based on SP coupling in graphene-semiconductor hybrid materials.