Directional emission from ZnO hexagonal disks.

Lots of theories and experiments have so far tried to acquire the directional emission with whispering-gallery modes (WGMs) from micro- and nanostructures, which will enhance the applications of micro- and nanoscaled whispering-gallery resonators in optoelectronic devices. Here for the first time we report a series of directional emission patterns with WGMs from the single ZnO hexagonal micro- and nanodisk. Based on the cathodeluminescence technique, we observed far-field emissions from ZnO hexagonal micro- and nanodisks in four geometries with different deformations. Mechanisms of directional emissions above were suggested. These investigations facilitated the applications of ZnO hexagonal micro- and nanodisks in photonic devices.