Data for publication entitled: Strong enhancement of two-photon absorption and emergence of unusual extinction saturation in silver sulfide quantum dots integrated with gold and silica nanostructures

Research data that was used to create the publication entitled: Strong Enhancement of Two-photon Absorption and Emergence of Unusual Extinction Saturation in Silver Sulfide Quantum Dots Integrated with Gold and Silica Nanostructures.

High-performance nonlinear optical nanostructures that function across a wide spectral range, from visible to near-infrared, are highly sought after for various photonic applications, including bioimaging and theranostics. In this study, we present a novel series of nanoparticles that integrate Ag2S quantum dots (QDs) with resonant plasmonic elements. These nanoparticles display exceptionally strong and sometimes unique nonlinear optical behaviors, which we have precisely measured using femtosecond Z-scan techniques.

Notably, we observe a dramatic 40-fold increase in the two-photon absorption efficiency of the QDs—a level of enhancement significantly surpassing previous records, which maxed out at a tenfold increase. Through numerical modeling and analysis of the spectral profile of the two-photon absorption enhancement, we identify the primary drivers of this enhancement: plasmonic local field effects and the coupling between plasmon resonances and QD excitons. Additionally, we report a newly observed phenomenon—a two-photon-induced saturation of extinction—evident in the distinctive Z-scan trace shapes, which we successfully modeled with a straightforward theoretical approach. Thanks to the robust quantitative results and the originality of our findings, this research holds significant potential to broaden current knowledge and inspire further exploration in nanotechnology and nonlinear optics. It paves the way for both fundamental studies and practical applications, including theranostics and the advancement of nonlinear optical devices.

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