Two-photon pumped random laser in nanocrystalline ZnO

Abstract

Thin film of ZnO nanoparticles with dimension of about 5–10nm were fabricated by the pulsed laser ablation method. By using a femtosecond laser beam at 700nm to pump micrometer-thick films the authors observed two-photon-induced lasing at 385nm. Experimentally obtained dependence of the threshold on the excitation spot radius r0 is closer to (1∕r02) than to (1∕r0), thus suggesting efficiency of the feedback by scattering-random lasing. The experimental data on nonlinear transmission of the film at the wavelength of pumping are presented.