Ultrafast resonant optical scattering from single gold nanorods: Large nonlinearities and plasmon saturation

TL;DR

This study demonstrates ultrafast nonlinear optical scattering from single gold nanorods, revealing large electron heating effects and unexpected plasmon damping, with implications for nanoplasmonic applications.

Contribution

It provides the first direct measurement of large nonlinearities in individual nanorods and uncovers electron heating as the dominant nonlinear mechanism.

Findings

Large nonlinear optical response observed in single nanorods

Nonlinearity primarily due to electron heating, not coherent plasmon oscillation

Reveals unanticipated damping of strongly driven plasmons

Abstract

We measure nonlinear optical scattering from individual Au nanorods excited by ultrafast laser pulses on resonance with their longitudinal plasmon mode. Isolating single rods removes inhomogeneous broadening and allows the measurement of a large nonlinearity, much greater than that of nanorod ensembles. Surprisingly, the ultrafast nonlinearity can be attributed entirely to heating of conduction electrons and does not exhibit any response associated with coherent plasmon oscillation. This indicates a previously unobserved damping of strongly driven plasmons.