Intensity-Dependent Enhancement of Saturable Absorption in PbS-Au4 Nanohybrid Composites: Evidence for Resonant Energy Transfer by Auger Recombination

TL;DR

This study demonstrates that the saturable absorption in PbS-Au4 nanohybrid composites is significantly enhanced by femtosecond laser excitation, due to resonant energy transfer via Auger recombination, with potential implications for nonlinear optical applications.

Contribution

It provides experimental evidence of intensity-dependent enhancement of saturable absorption in PbS-Au4 nanohybrids caused by resonant energy transfer through Auger recombination.

Findings

Saturable absorption coefficient increases with excitation irradiance.

Enhancement of nearly fourfold compared to pure PbS quantum dots.

Resonant energy transfer via Auger recombination is the key mechanism.

Abstract

Intensity-dependent enhancement of saturable absorption in a film of PbS-Au4 nanohybrid composites has been observed by femtosecond time-resolved transient absorption measurement at 780 nm. The nonlinear absorption coefficient of saturable absorption in PbS-Au4 nanohybrid composites is found to be dependent on excitation irradiance and it is determined to be -2.9 cm/GW at 78 GW/cm2, an enhancement of nearly fourfold in comparison with that of pure PbS quantum dots (QDs). The enhancement is attributed to excitation of surface plasmon by resonant energy transfer between PbS QDs and Au nanoparticles through Auger recombination.