Nonlinear Absorption and Fluorescence in ZnO and ZnO–Au Nanostructures

Abstract

This paper investigates whether coupling gold nanoparticles to nanostructured zinc oxide enhances fluorescence emission, to produce efficient nanoscale UV emitters that radiate through nonlinear optical absorption processes. The z‐scan technique is used to measure nonlinear absorption simultaneously with measurements of nonlinear‐absorption‐induced fluorescence in zinc oxide nanostructures and hybrid zinc oxide–gold nanostructures. This allows for better determination of the nonlinear excitation and energy dissipation pathways. The measurements show that the nonlinear absorption of the hybrid structures is enhanced by up to two orders of magnitude compared to the pure zinc oxide nanostructures. However, it is found that the increase in nonlinear absorption does not correspond to an equivalent increase in fluorescence due to the competition between two‐photon absorption and excited state absorption.