The nonlinear optical absorption and optical limiting properties of noble metal-doped ZnO films

Abstract

Herein, pure ZnO, Ag-doped ZnO, and Cu-doped ZnO films with excellent ultrafast (femtosecond) nonlinear absorption/limiting behavior were deposited on quartz substrates by magnetron sputtering. From the open-aperture Z-scan result, under femtosecond pulses, the strong two-photon absorption (TPA) behavior of metal-doped ZnO was found, and the absorption coefficient was found to be several times that of pure ZnO, which will expand the design and application strategies of metal-doped wide-gap semiconductor materials in the field of nonlinear devices. Moreover, the samples exhibited superior optical limiting behavior with respect to the optical modulation characteristics of the input-output laser. The mechanism of optical limiting effects is induced by the TPA-induced reverse saturable absorption of the deep level and low excited state processes.