Dual coherent and incoherent two-photon luminescence in single gold nanorods revealed by polarization and time-resolved nonlinear autocorrelation

• DOI: 10.1364/josab.36.001931
• Publication Date: 2019-06-20T16:01:30Z
• Authors: Dan Xie; François O. Laforge; Ilya Grigorenko; Herschel A. Rabitz
• Keywords: Nanorod

It is well known that gold nanorods (AuNRs) readily emit two-photon luminescence (TPL) when excited by a broad bandwidth laser pulse tuned to the AuNRs' localized surface plasmon resonance. The nature of mechanism (i.e., especially its degree coherence) under active debate. In this work, we measured TPL emission from single while varying angle θ between linearly polarized electric field and nanorod's orientation. Data were best fit with linear combination cos4 cos2 functions. While former function may represent signals arising both coherent incoherent processes, later indicative purely process. To further validate assessment, in time-resolved collinear autocorrelation setup. signal exhibited large peak at zero delay, which characteristic absorption two lower intensity wings extending few picoseconds, demonstrates existence long-lived intermediate state contributes two-step We conclude AuNRs can result processes.