46 research outputs found
Cooling Dynamics of a Gold Nanoparticle in a Host Medium Under Ultrafast Laser Pulse Excitation: A Ballistic-Diffusive Approach
We present a numerical model allowing to determine the electron and lattice
temperature dynamics in a gold nanoparticle under subpicosecond pulsed
excitation, as well as that of the surrounding medium. For this, we have used
the electron-phonon coupling equation in the particle with a source term linked
with the laser pulse, and the ballistic-diffusive equations for heat conduction
in the host medium. Our results show that the heat transfer rate from the
particle to the matrix is significantly smaller than the prediction of
Fourier's law. Consequently, the particle temperature rise is much larger and
its cooling dynamics is much slower than that obtained using Fourier's law,
which is attributed to the nonlocal and nonequilibrium heat conduction in the
vicinity of the nanoparticle. These results are expected to be of great
importance for interpreting pump-probe experiments performed on single
nanoparticles or nanocomposite media
Thermal Excitation of Broadband and Long-range Surface Waves on SiO 2 Submicron Films
We detect thermally excited surfaces waves on a submicron SiO 2 layer,
including Zenneck and guided modes in addition to Surface Phonon Polaritons.
The measurements show the existence of these hybrid thermal-electromagnetic
waves from near-(2.7 m) to far-(11.2 m) infrared. Their propagation
distances reach values on the order of the millimeter, several orders of
magnitude larger than on semi-infinite systems. These two features, spectral
broadness and long range propagation, make these waves good candidates for
near-field applications both in optics and thermics due to their dual nature.Comment: Applied Physics Letters, American Institute of Physics, 201
Photo-induced ultrafast optical and thermal responses of gold nanoparticles
PARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF
Nonthermal model for ultrafast laser-induced plasma generation around a plasmonic nanorod
International audienc
Large and Ultrafast Optical Response of a One-Dimensional Plasmonic-Photonic Cavity
International audienceThe resonant coupling of a localized surface plasmon mode and a cavity mode in a photonic crystal has been recently shown to strongly tailor the stationary optical response of gold nanoparticles. Here, we demonstrate that this can be further exploited for controlling light on an ultrashort time scale. The stationary and ultrafast optical responses of such a plasmonic-photonic cavity are investigated numerically. We show that the transient photo-induced change of the optical transmittance of a bare nanocomposite thin film can be amplified up to 60 times once resonantly coupled to the cavity mode in the hybrid device, despite the degradation of this mode due to absorption losses. In addition, different all-optical, ultrafast, efficient, and reversible photonic functions (increase or decrease of the signal intensity, transient spectral shift of the cavity mode) can be achieved depending on the spectral position of the transmitted mode tuned by varying the angle of incidence. The transient modification of the signal intensity is predicted to reach about 300 % after a subpicosecond rise time when the defect mode matches the plasmon resonance
Absorption of Ultrashort Laser Pulses by Plasmonic Nanoparticles: Not Necessarily What You Might Think
International audienc