Gold-nanoparticle-assisted random lasing from powdered GaN.

We demonstrate Au-nanoparticle-assisted random lasing from a powdered GaN sample. In the presence of Au nanoparticles on GaN powder surfaces, several lasing lines are observed in photoexcited luminescence spectra near the center of the GaN band-edge emission peak. The random lasing is considered to arise from a decrease in the lasing threshold due to the suppression of crystal defect loss by surface plasmon excitation on Au. From spatially resolved lasing emission spectra and their FT analysis results, the formation of random lasing cavities at different spatial positions is confirmed. The size of the random lasing spot is determined to be larger than that of the scattered light speckle of the pumping source on a thin powdered GaN sample.