Optical Characterization of ZnO Microsphere Produced by Laser Ablation in Air

We have succeeded in growing the ZnO microspheres by a simple laser ablation in the air, and we have obtained UV whispering-gallery-mode (WGM) lasing from the sphere under pulsed laser excitation. In this study, we observed resonances of WGM in visible region under cw laser pumping. In addition, possible refractive index of the ZnO microsphere was estimated from the WGM peaks. Furthermore, we obtained room-temperature electroluminescence from the ZnO microsphere/p-GaN heterojunction under forward bias.