Discrete-mode ZnO microparticle random laser

A random laser incorporating irregular-shaped ZnO microparticles exhibits a small number of lasing lines with stable lasing intensities and negligibly low background emission. This unique feature is in direct contrast to that observed for a conventional ZnO nanoparticle film random laser. Gain competition between the discrete laser modes also occurs in this microparticle random laser. These lasing characteristics are because of the intra-particle confinement of the laser cavity modes in each ZnO microparticle.