Harmonic-Induced Plasmonic Resonant Energy Transfer between Metal and Semiconductor Nanoparticles

TL;DR

This paper introduces a novel harmonic-induced plasmonic energy transfer mechanism in metal-semiconductor heterostructures, enabling tunable, ultrafast energy transfer with potential applications in nanodevices and imaging.

Contribution

It demonstrates a new HIPRET mechanism linking metal and semiconductor plasmons, with experimental and simulation validation, advancing nonlinear nanophotonics.

Findings

Faster plasmon relaxation in heterostructures (690 fs) compared to CuS (929 fs).

Confirmation of d^(-6) dependence of surface-dipole interactions.

Observation of harmonic-induced coupling between CuS and Au LSPRs.

Abstract

Heterostructures combining two or more metal and/or semiconductor nanoparticles exhibit enhanced upconversion arising from localized surface plasmon resonances (LSPRs). However, coupled plasmon-exciton systems are slowed by excitonic relaxation and metallic multi-plasmon systems are not broadly tunable. Here, we describe a heterostructure in which insulating alumina layers vary separation between CuS and Au nanoparticles, allowing experimental confirmation of the d^(-6) dependence typical of surface-dipole mediated interactions between Au and CuS plasmons, as demonstrated in Lumerical simulations. Transient-absorption spectroscopy shows faster plasmon relaxation in heterostructured Au/CuS (690 fs) than CuS nanoparticles (929 fs), signifying direct energy transfer. Moreover, coupling between the second-harmonic LSPRs of CuS and the fundamental LSPR in Au is evident in nonlinear absorption measurement. This defines a novel harmonic-induced plasmonic resonant energy transfer (HIPRET) dynamic linking the metallic Au plasmon and the broad semiconductor plasmon in CuS. This prototype for tunable, ultrafast plasmonic upconversion exemplifies a strategy for high-efficiency nonlinear nanodevices that have promising applications in photocatalysis, parametric down-conversion and biomedical imaging.