Coherent scattering in hybrid GaN meta-surfaces with ZnO nanoantennae

Nonlinear optical microcavity structures within GaN meta-surfaces monolithically integrated with ZnO nanoantennae form an ideal platform for realizing tunable nanophotonic sources and directional emitters. Highly efficient second harmonic generation (SHG) is demonstrated from GaN micro-pyramids selectively grown on a wafer-scale substrate to form a meta-surface with ZnO nanoantennae at the tip of each pyramid. The nonlinear light generation from this cavity-based antenna depends on the relative competition of the second and third-order nonlinear process. The selective excitation of a single nanoantenna within the meta-structure can control the nonlinear light generation process. The energy density and frequency of the excitation source compared to the semiconductor's bandgap influences the coherent scattering and directionality of the emission process from the excitation of the meta-structure. The efficiency and directionality of the SHG signal depend on the localized spatial excitation of the ZnO nanorod and GaN micro-pyramid.