Colloidal Au–CsPbBr3 for nonlinear saturable absorption effects

Abstract

We demonstrate the nonlinear saturable absorption effects of colloidal Au–CsPbBr3 inorganic nanocrystals (INCs) that may useful as a saturable absorber in passively mode-locked pulse lasers. Femtosecond open-aperture Z-scan technique is responsible for measuring the nonlinear saturable absorption effects at 800 nm with a repetition rate of 76 MHz and a laser pulse duration of 130 fs. Compared to colloidal pure-CsPbBr3 INCs, the nonlinear saturable absorption coefficient β ~ 2.34 × 10–10 cm/W and the second-order absorption cross section σ2 ~ 2.13 × 104 GM of colloidal Au–CsPbBr3 INCs can be improved by up to one order of magnitude at the Au-doping concentration of 3.5 mmol/L, thanks to an obviously cocked tail absorption from visible to near-infrared spectral region through the localized surface plasmon-induced charge transition at Au–CsPbBr3 INCs interface rather than the light scattering of the deposited Au nanoparticles. And the deposited Au nanoparticles have not changed the crystalline structure, stability, and morphology of colloidal pure-CsPbBr3 INCs. As a result, colloidal Au–CsPbBr3 INCs are expected to become a potential saturable absorption candidate material used in passively mode-locked pulse lasers.