757 research outputs found
Two-fluid hydrodynamic model for semiconductors
The hydrodynamic Drude model (HDM) has been successful in describing the
optical properties of metallic nanostructures, but for semiconductors where
several different kinds of charge carriers are present, an extended theory is
required. We present a two-fluid hydrodynamic model for semiconductors
containing electrons and holes (from thermal or external excitation) or light
and heavy holes (in -doped materials). The two-fluid model predicts the
existence of two longitudinal modes, an acoustic and an optical, whereas only
an optical mode is present in the HDM. By extending nonlocal Mie theory to two
plasmas, we are able to simulate the optical properties of two-fluid
nanospheres and predict that the acoustic mode gives rise to peaks in the
extinction spectra that are absent in the HDM.Comment: Accepted in PRB. 17 pages, 9 figures, 1 tabl
Time-dependent transport of a localized surface plasmon through a linear array of metal nanoparticles: Precursor and normal mode contributions
We theoretically investigate the time-dependent transport of a localized
surface plasmon excitation through a linear array of identical and
equidistantly spaced metal nanoparticles. Two different signals propagating
through the array are found: one traveling with the group velocity of the
surface plasmon polaritons of the system and damped exponentially, and the
other running with the speed of light and decaying in a power-~law fashion, as
and for the transversal and longitudinal polarizations,
respectively. The latter resembles the Sommerfeld-Brillouin forerunner and has
not been identified in previous studies. The contribution of this signal
dominates the plasmon transport at large distances. In addition, even though
this signal is spread in the propagation direction and has the lateral
dimension larger than the wavelength, the field profile close to the chain axis
does not change with distance, indicating that this part of the signal is
confined to the array.Comment: 13 pages, 10 figures, to be published in PR
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