3D resonator based on luminescence enhanced by both polarized, size-dependent whispering gallery modes and Fabry–Pérot waveguide modes in individual ZnO micro- and nanonails

A 3D resonator based on both polarized, size-dependent whispering gallery (WG) modes and Fabry-Pérot (FP) waveguide modes has been achieved using individual ZnO micro- and nanonails. Monochromatic cathodoluminescence images of the ZnO micro- and nanonails show that enhanced luminescence intensity is focused on two regions, i.e., the profile and the center of the micro- and nanonails. The luminescence from the center region is attributed to the emission enhanced by 1D FP waveguide modes, and that from the hexagonal profile is attributed to the emission enhanced by both polarized, size-dependent 2D WG modes when an individual ZnO nanocolumn is regarded as an optical resonator. Theoretical calculations and computer simulations based on the finite element method (FEM) with perfectly matched layer (PML) boundary conditions are performed, and the corresponding results are close to the experimental phenomena.