Two-photon induced photoluminescence and lasing in pulsed-laser deposited ZnO nanostructures pumped by continuous wave He-Ne laser

We report on two-photon induced photoluminescence studies on the ZnO nanostructures obtained via pulsed laser deposition technique. The photoluminescence is recorded using a continuous wave He-Ne laser at 632.8 nm with a maximum power of around 31 mW. Two-photon induced emissions have been attributed to transitions via zinc interstitials and oxygen vacancy, respectively. These emissions also show modulations indicating the lasing behavior that is attributed to the formation of whispering gallery modes.