Whispering gallery modes and random lasing in ZnO microstructures

Abstract

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 µm 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.