Spheroidal particle plasmons in amplifying media

Smuk, Andrei Y.; Lawandy, N. M.

doi:10.1007/s00340-006-2329-4

Cited by 12 publications

(9 citation statements)

References 14 publications

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“…Changes in shape, aspect ratios or spasing modes may only be used to shift the spasing eigenfrequency towards those minima, but not to change them in any way. Although similar results have been derived before for the specific example of spheroids , by using general energy considerations , or by using quantum mechanics , it seems that they have been widely overlooked given the large body of publications named previously, where one tried to improve spaser thresholds using specific nanoparticle geometries, and modes.…”

Section: Introductionsupporting

confidence: 60%

“…The denominator of equation (up to a constant factor) can be rewritten in the form

D = ɛ_{G} + N ɛ_{M}

with

N = L / (1 - L)

in case of the dipolar resonance of rotational ellipsoids, as was used by Smuk and Lawandy . In the current paper, however, we argue that in the quasi‐static limit the resonant denominator may be rewritten in the form of equation for any shape and any multipolar order.…”

Section: Minimal Threshold For the Quasi‐static Limitmentioning

confidence: 91%

“…Spheroidal nanoparticles in gain materials were studied before in the electrostatic limit , and experimental results for aggregates of nanoparticles were simulated with spheroids as well . In this section, we expand the theoretical considerations to spheroids of finite size where radiation damping and retardation are taken into account.…”

Section: Gain Thresholds For Spheroidal Spasers Including Retardationmentioning

confidence: 99%

“…In these papers, the influence of the nanostructures’ geometry on the spasing modes and the generation thresholds was studied with different degrees of detail. Earlier considerations on these topics are given in the papers . Further, the interaction of metal nano‐particles with a single or multiple active Hertzian dipole emitters was investigated in a series of numerical studies .…”

Section: Introductionmentioning

confidence: 99%

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Minimal spaser threshold within electrodynamic framework: Shape, size and modes

2015

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It is known (yet often ignored) from quantum mechanical or energetic considerations, that the threshold gain of the quasi‐static spaser depends only on the dielectric functions of the metal and the gain material. Here, we derive this result from the purely classical electromagnetic scattering framework. This is of great importance, because electrodynamic modelling is far simpler than quantum mechanical one. The influence of the material dispersion and spaser geometry are clearly separated; the latter influences the threshold gain only indirectly, defining the resonant wavelength. We show that the threshold gain has a minimum as a function of wavelength. A variation of nanoparticle shape, composition, or spasing mode may shift the plasmonic resonance to this optimal wavelength, but it cannot overcome the material‐imposed minimal gain. Furthermore, retardation is included straightforwardly into our framework; and the global spectral gain minimum persists beyond the quasi‐static limit. We illustrate this with two examples of widely used geometries: Silver spheroids and spherical shells embedded in and filled with gain materials.

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Section: Introductionsupporting

confidence: 60%

“…The denominator of equation (up to a constant factor) can be rewritten in the form

D = ɛ_{G} + N ɛ_{M}

with

N = L / (1 - L)

Section: Minimal Threshold For the Quasi‐static Limitmentioning

confidence: 91%

Section: Gain Thresholds For Spheroidal Spasers Including Retardationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Minimal spaser threshold within electrodynamic framework: Shape, size and modes

2015

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“…This problem could be circumvented by introducing gain in the system. Studies have been made in such a way with metallic nanoparticles embedded in a gain medium both numerically with dye molecules 6 or quantum dots 7,8 and experimentally 10 . Seidel et al reported the first experiment demonstrating the amplification of surface plasmons on a flat silver film surrounded by a solution of dye molecules 11 .…”

Section: Introductionmentioning

confidence: 99%

Quantum theory of spontaneous and stimulated emission of surface plasmons

et al. 2010

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We introduce a quantization scheme that can be applied to surface waves propagating along a plane interface. An important result is the derivation of the energy of the surface wave for dispersive non-lossy media without invoking any specific model for the dielectric constant. Working in Coulomb's gauge, we use a modal representation of the fields. Each mode can be associated with a quantum harmonic oscillator. We have applied the formalism to derive quantum-mechanically the spontaneous emission rate of surface plasmon by a two-level system. The result is in very good agreement with Green's tensor approach in the non-lossy case. Green's approach allows also to account for losses, so that the limitations of a quantum approach of surface plasmons are clearly defined. Finally, the issue of stimulated versus spontaneous emission has been addressed. Because of the increasing density of states near the asymptote of the dispersion relation, it is quantitatively shown that the stimulated emission probability is too small to obtain gain in this frequency region.

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