Enhancement of nonlinear optical property of Cu 2 O/Ag/Cu 2 O composite films induced by laser irradiation

In this paper, Cu2O/Ag/Cu2O nanocomposite films were obtained by controlling thermal oxidation Cu/Ag/Cu alloy films and then modified by laser irradiation under ambient condition. The effects of laser irradiation on the surface morphology, structure, optical properties and nonlinear performance of the sample were investigated. Those results indicate that the improvement of crystal quality, enhancement of Ag plasma peak and a large number of oxygen vacancy defects could be induced by laser irradiation. A switch from saturated absorption to reverse saturated absorption was observed in all samples with the excitation energy increasing. Compared with either single-layer or bilayer sample, the third-order nonlinear coefficient (β) of the sandwich structure samples was increased by 3.73 times after laser irradiation. In addition, the improvement of nonlinear performance of as-irradiated samples was also confirmed by finite difference time domain (FDTD) simulation results.