Exciton and electron-hole plasma lasing in ZnO dodecagonal whispering-gallery-mode microcavities at room temperature

Dodecagonal ZnO microrods were fabricated by vapor transport method. A dodecagonal ZnO microrod with diameter of 6.35 μm was employed as a whispering gallery mode microcavity, the low threshold exciton lasing was stimulated. In another smaller microrod, the electron-hole plasma lasing was observed under intense excitation as the carrier density was larger than the Mott transition density. The interference condition in the dodecagonal cavity was deduced, and the mode structures were investigated. Compared to the hexagonal microcavity with same diameter, the dodecagonal microcavity has higher lasing performance.