Enhanced nonlinear optical properties of RGO via Au modification: application for Q-switched waveguide laser

Abstract

Both reduced graphene oxide (RGO) and gold (Au) nanoparticles have shown distinct nonlinear optical characteristics, such as saturable absorption, that are appropriate for generating ultrashort pulse lasers. Unfortunately, there are no studies of Q-switched waveguide lasers using RGO and RGO modified with Au nanoparticles (Au-RGO) as saturable absorbers. Here we perform the pump-probe experiments to investigate the nonlinear optical absorption properties of RGO and Au-RGO. Our results show that, compared with RGO, Au-RGO has advantages of a higher modulation depth, faster optical response and wavelength-independent nonlinear absorption, which demonstrates that nonlinear optical properties of Au-RGO have been enhanced owing to the Au nanoparticles. Moreover, the laser emission of Q-switched Nd:YAG channel waveguidewith Au-RGO as a saturable absorber has been obtained. In comparison with the waveguide laser system utilizing RGO, the Q-switched laser observed with Au-RGO exhibits a shorter pulse duration and a higher repetition frequency, indicating the potential application of Au-RGO as a cost-effective saturable absorber in the pulsed waveguide laser systems.