High-power single-mode ZnO thin-film random lasers

The possibilities to realize high-power single-mode ultraviolet lasing in highly disordered zinc oxide (ZnO) thin films are investigated. An effective one-dimensional time-domain traveling-wave model is developed to simulate random laser action in ZnO thin-film waveguides with ridge structure. Spectral and spatial redistributions of lasing modes, due to lasing mode localization and repulsion, are shown in highly disordered media. Hence, by controlling the photon density distribution, selective excitation of lasing modes can be achieved. A coupled-cavity ZnO thin-film random laser is also proposed to achieve high-power single-mode operation under nonuniform pumping. Preliminary experimental results have verified the possibility to realize high-power single-mode emission by the use of the proposed coupled-cavity design.