Analysis of Random Lasers Threshold in ZnO Nanoparticle Based Cavity

In this paper we investigate lasing threshold of 1D-ZnO based random lasers by using time domain travelling wave model. It is demonstrated that when pump intensity is less than threshold output intensity is negligible. In this condition spontaneous emission is the main emission in the medium. By increasing pump intensity above threshold stimulated emission starts and causes rapid increase in the output intensity. Analysis of temporal response shows quick excitonic recombination as a result of starting stimulated emission. It is shown that lasing threshold is dependent on pump area. It means that the laser threshold is higher for smaller pump area.