Whispering gallery modes and random lasing in ZnO microstructures

Hexagonal ZnO microdiscs and hemispherical ZnO microstructure built from hierarchical nanostructures have been grown by metal-organic chemical vapour deposition and carbothermal evaporation technologies, respectively. The technologies ensure as high an optical quality of the produced structures so as to act as a gain medium for stimulated emission in the ultraviolet spectral region in combination with high quality factor laser resonators. The ZnO microdisc resonators with diameters of around 1.8 mu m and thicknesses of 100 nm support whispering gallery modes with a quality factor of 640, while the lasing in the hemispherical ZnO microstructure represents a combination of whispering gallery modes in microrods with a quality factor of 640-800 and random lasing in an array of ZnO nanowires with a quality factor of around 3000.