Blue-emitting ZnSe random laser

Abstract

We demonstrate a blue-emitting semiconductor random laser using a thin ZnSe powered film at room and low temperatures. Below the threshold excitation, we observe a broad spontaneous emission band centered at ~470 nm due to the excitonic transitions in ZnSe particles. Above the threshold excitation, several discrete lasing lines caused by the light amplification in closed-loop paths and emitted in all directions were observed near the center of the spontaneous emission band (~475 nm). The linewidth of each discrete lasing line is less than 0.4 nm. Lasing threshold power density is determined to be ~700 kW/cm². The effective cavity diameter D_eff is also estimated to be ~6 μm from the experimental lasing spectrum by performing Fourier transform analysis. The temperature dependence of the lasing characteristics in ZnSe random laser is also investigated and found that decreasing temperature shifts the discrete lasing lines toward higher-energy side with increasing their intensities.