Nonlinear Optical Properties of Plasmon–Exciton Nanostructures Based on PbS Quantum Dots and Gold Nanorods in the Field of Nanosecond Laser Pulses

We present the results of our study of nonlinear optical response observed in plasmon–exciton nanostructures based on PbS quantum dots passivated with thioglycolic acid and gold nanorods under the influence of 10 ns second harmonic pulses (532 nm) of Nd³⁺:YAG laser. We show that the association of components of a hybrid nanostructure leads to increase in the reverse saturable absorption in PbS quantum dots against the background of nonlinear refraction. Coating quantum dots with a monolayer of SiO₂ reduces this effect due to blocking the process of phototransfer of charge from a quantum dot to a metal nanoparticle, which is confirmed by the quenching and reduction in the luminescence lifetime of PbS quantum dots in the presence of gold nanorods.