65 research outputs found
Surface scattering contribution to the plasmon width in embedded Ag nanospheres
Nanometer-sized metal particles exhibit broadening of the localized surface
plasmon resonance (LSPR) in comparison to its value predicted by the classical
Mie theory. Using our model for the LSPR dependence on non-local surface
screening and size quantization, we quantitatively relate the observed plasmon
width to the nanoparticle radius and the permittivity of the surrounding
medium . For Ag nanospheres larger than 8 nm only the non-local
dynamical effects occurring at the surface are important and, up to a diameter
of 25 nm, dominate over the bulk scattering mechanism. Qualitatively, the LSPR
width is inversely proportional to the particle size and has a nonmonotonic
dependence on the permittivity of the host medium, exhibiting for Ag a maximum
at . Our calculated LSPR width is compared with recent
experimental data.Comment: 11 pages, 4 figures. Accepted for publication in Optics Expres
Diffuse Surface Scattering in the Plasmonic Resonances of Ultra-Low Electron Density Nanospheres
Localized surface plasmon resonances (LSPRs) have recently been identified in
extremely diluted electron systems obtained by doping semiconductor quantum
dots. Here we investigate the role that different surface effects, namely
electronic spill-out and diffuse surface scattering, play in the optical
properties of these ultra-low electron density nanosystems. Diffuse scattering
originates from imperfections or roughness at a microscopic scale on the
surface. Using an electromagnetic theory that describes this mechanism in
conjunction with a dielectric function including the quantum size effect, we
find that the LSPRs show an oscillatory behavior both in position and width for
large particles and a strong blueshift in energy and an increased width for
smaller radii, consistent with recent experimental results for photodoped ZnO
nanocrystals. We thus show that the commonly ignored process of diffuse surface
scattering is a more important mechanism affecting the plasmonic properties of
ultra-low electron density nanoparticles than the spill-out effect.Comment: 19 pages, 5 figures. Accepted for publication in The Journal of
Physical Chemistry Letter
Realizing strong light-matter interactions between single nanoparticle plasmons and molecular excitons at ambient conditions
Realizing strong light-matter interactions between individual 2-level systems
and resonating cavities in atomic and solid state systems opens up
possibilities to study optical nonlinearities on a single photon level, which
can be useful for future quantum information processing networks. However,
these efforts have been hampered by the unfavorable experimental conditions,
such as cryogenic temperatures and ultrahigh vacuum, required to study such
systems and phenomena. Although several attempts to realize strong light-matter
interactions at room-temperature using so-called plasmon resonances have been
made, successful realizations on the single nanoparticle level are still
lacking. Here, we demonstrate strong coupling between plasmons confined within
a single silver nanoprism and excitons in molecular J-aggregates at ambient
conditions. Our findings show that the deep subwavelength mode volumes, ,
together with high quality factors, , associated with plasmons in the
nanoprisms result in strong coupling figure-of-merit -- as high as
~m -- a value comparable to state-of-art
photonic crystal and microring resonator cavities, thereby suggesting that
plasmonic nanocavities and specifically silver nanoprisms can be used for
room-temperature quantum optics
Strong coupling out of the blue: an interplay of quantum emitter hybridization with plasmonic dark and bright modes
Strong coupling between a single quantum emitter and an electromagnetic mode
is one of the key effects in quantum optics. In the cavity QED approach to
plasmonics, strongly coupled systems are usually understood as
single-transition emitters resonantly coupled to a single radiative plasmonic
mode. However, plasmonic cavities also support non-radiative (or "dark") modes,
which offer much higher coupling strengths. On the other hand, realistic
quantum emitters often support multiple electronic transitions of various
symmetry, which could overlap with higher order plasmonic transitions -- in the
blue or ultraviolet part of the spectrum. Here, we show that vacuum Rabi
splitting with a single emitter can be achieved by leveraging dark modes of a
plasmonic nanocavity. Specifically, we show that a significantly detuned
electronic transition can be hybridized with a dark plasmon pseudomode,
resulting in the vacuum Rabi splitting of the bright dipolar plasmon mode. We
develop a simple model illustrating the modification of the system response in
the "dark" strong coupling regime and demonstrate single photon non-linearity.
These results may find important implications in the emerging field of room
temperature quantum plasmonics
Suppression of photo-oxidation of organic chromophores by strong coupling to plasmonic nanoantennas
Intermixed light-matter quasiparticles - polaritons - possess unique optical
properties owned to their compositional nature. These intriguing hybrid states
have been extensively studied over the past decades in a wide range of
realizations aiming at both basic science and emerging applications. However,
recently it has been demonstrated that not only optical, but also
material-related properties, such as chemical reactivity and charge transport,
may be significantly altered in the strong coupling regime of light-matter
interactions. Here, we show that a nanoscale system, comprised of a plasmonic
nanoprism strongly coupled to excitons in J-aggregated form of organic
chromophores, experiences modified excited state dynamics and therefore
modified photo-chemical reactivity. Our experimental results reveal that
photobleaching, one of the most fundamental photochemical reactions, can be
effectively controlled and suppressed by the degree of plasmon-exciton coupling
and detuning. In particular, we observe a 100-fold stabilization of organic
dyes for the red-detuned nanoparticles. Our findings contribute to
understanding of photochemical properties in the strong coupling regime and may
find important implications for the performance and improved stability of
optical devices incorporating organic dyes.Comment: 5 figures; includes Supplementary Material
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