TY - JOUR
T1 - Dual coherent and incoherent two-photon luminescence in single gold nanorods revealed by polarization and time-resolved nonlinear autocorrelation
AU - Xie, Dan
AU - Laforge, François O.
AU - Grigorenko, Ilya
AU - Rabitz, Herschel A.
N1 - Publisher Copyright:
© 2019 Optical Society of America.
PY - 2019
Y1 - 2019
N2 - It is well known that gold nanorods (AuNRs) readily emit two-photon luminescence (TPL) when excited by a broad bandwidth laser pulse that is tuned to the AuNRs’ localized surface plasmon resonance. The nature of the mechanism (i.e., especially its degree of coherence) is under active debate. In this work, we measured the TPL emission from single nanorods while varying the angle θ between the linearly polarized laser electric field and the nanorod’s orientation. Data were best fit with a linear combination of cos4 θ and cos2 θ functions. While the former function may represent TPL signals arising from both coherent and incoherent processes, the later function is indicative of a purely incoherent process. To further validate this assessment, we measured TPL emission from single nanorods in a time-resolved collinear autocorrelation setup. The autocorrelation signal exhibited a large peak at zero delay, which is characteristic of coherent two-photon absorption and two lower intensity wings extending to a few picoseconds, which demonstrates the existence of a long-lived intermediate state that contributes to a two-step incoherent absorption process. We conclude that TPL in AuNRs can result from a combination of coherent and incoherent absorption processes.
AB - It is well known that gold nanorods (AuNRs) readily emit two-photon luminescence (TPL) when excited by a broad bandwidth laser pulse that is tuned to the AuNRs’ localized surface plasmon resonance. The nature of the mechanism (i.e., especially its degree of coherence) is under active debate. In this work, we measured the TPL emission from single nanorods while varying the angle θ between the linearly polarized laser electric field and the nanorod’s orientation. Data were best fit with a linear combination of cos4 θ and cos2 θ functions. While the former function may represent TPL signals arising from both coherent and incoherent processes, the later function is indicative of a purely incoherent process. To further validate this assessment, we measured TPL emission from single nanorods in a time-resolved collinear autocorrelation setup. The autocorrelation signal exhibited a large peak at zero delay, which is characteristic of coherent two-photon absorption and two lower intensity wings extending to a few picoseconds, which demonstrates the existence of a long-lived intermediate state that contributes to a two-step incoherent absorption process. We conclude that TPL in AuNRs can result from a combination of coherent and incoherent absorption processes.
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U2 - 10.1364/JOSAB.36.001931
DO - 10.1364/JOSAB.36.001931
M3 - Article
AN - SCOPUS:85069619757
SN - 0740-3224
VL - 36
SP - 1931
EP - 1936
JO - Journal of the Optical Society of America B: Optical Physics
JF - Journal of the Optical Society of America B: Optical Physics
IS - 7
ER -