Abstract

We observed double threshold behavior with the lasing peak blue-shift in a resonance-controlled ZnO nanopowder random laser, which was never before observed in conventional ZnO random lasers. From an analysis, we found that the lasing at 1^st threshold appeared around exciton recombination energies and the lasing threshold carrier density was comparable to the Mott density, whereas the lasing at 2^nd threshold was induced by the population inversion accompanied by electron-hole plasma recombination like conventional ZnO random lasers. These results suggested the possibility that the strong coupling of excitons and a single localized mode in the resonance-controlled random laser could be achieved.

© 2015 Optical Society of America