Observation of amplified spontaneous emission in Cd1-xZnxSe/ZnSe alloyed quantum dots through CW pumping

Abstract

Colloidal quantum dots (QDs) have attracted much attention due to their optical tunability and application as a unique solution processable gain medium in lasers. Many research groups over the world have successfully attained amplification from Cd-based QDs through femtosecond (fs) and nanosecond (ns) pumping. However, for the wide application of QD-based lasers, an operation in the CW regime is much more favorable. Here, we present a critical step towards this goal by demonstrating CW laser (532 nm) pumped amplified spontaneous emission (ASE) in Cd1-xZnxSe/ZnSe alloyed core QDs dispersed in toluene at room temperature. Alloyed core QDs show lower non radiative transitions, which has been demonstrated by TA dynamics in this report. The threshold level for CW ASE is observed to be 31 W cm-2. These results indicate that these QDs can sustain CW-stimulated emission at room temperature, and can be widely applicable by further optimizing the QD material quality in order to have a low amplification threshold.