Light Localization and Stimulated Emission in InGaN/GaN Nanocolumns

We report the dependence of stimulated emission phenomena on randomness in a collection of regularly arranged InGaN/GaN nanocolumns. By comparing the stimulated emission behavior for two samples with different degrees of randomness, we found that localization effects are inevitable even in the almost perfect sample, and several modes partially overlapping in space will compete with each other. The ultrafast dynamics of stimulated emission under femtosecond pulsed laser excitation were also investigated, and the emission peaks were observed to change with time.