4,587 research outputs found
Cryogenic spectroscopy of ultra-low density colloidal lead chalcogenide quantum dots on chip-scale optical cavities towards single quantum dot near-infrared cavity QED
We present evidence of cavity quantum electrodynamics from a sparse density
of strongly quantum-confined Pb-chalcogenide nanocrystals (between 1 and 10)
approaching single-dot levels on moderately high-Q mesoscopic silicon optical
cavities. Operating at important near-infrared (1500-nm) wavelengths, large
enhancements are observed from devices and strong modifications of the QD
emission are achieved. Saturation spectroscopy of coupled QDs is observed at
77K, highlighting the modified nanocrystal dynamics for quantum information
processing.Comment: * new additional figures and text * 10 pages, 5 figure
Highly photo-stable Perovskite nanocubes: towards integrated single photon sources based on tapered nanofibers
The interest in perovskite nanocrystals (NCs) such as CsPbBr for quantum
applications is rapidly raising, as it has been demonstrated that they can
behave as very efficient single photon emitters. The main problem to tackle in
this context is their photo-stability under optical excitation. In this
article, we present a full analysis of the optical and quantum properties of
highly efficient perovskite nanocubes synthesized with an established method,
which is used for the first time to produce quantum emitters, and is shown to
ensure an increased photostability. These emitters exhibit reduced blinking
together with a strong photon antibunching. Remarkably these features are
hardly affected by the increase of the excitation intensity well above the
emission saturation levels. Finally, we achieve for the first time the coupling
of a single perovskite nanocube with a tapered optical nanofiber in order to
aim for a compact integrated single photon source for future applications
Excitation Enhancement of a Quantum Dot Coupled to a Plasmonic Antenna
Plasmonic antennas are key elements to control the luminescence of quantum
emitters. However, the antenna's influence is often hidden by quenching losses.
Here, the luminescence of a quantum dot coupled to a gold dimer antenna is
investigated. Detailed analysis of the multiply excited states quantifies the
antenna's influence on the excitation intensity and the luminescence quantum
yield separately
Intensity-Dependent Enhancement of Saturable Absorption in PbS-Au4 Nanohybrid Composites: Evidence for Resonant Energy Transfer by Auger Recombination
Intensity-dependent enhancement of saturable absorption in a film of PbS-Au4
nanohybrid composites has been observed by femtosecond time-resolved transient
absorption measurement at 780 nm. The nonlinear absorption coefficient of
saturable absorption in PbS-Au4 nanohybrid composites is found to be dependent
on excitation irradiance and it is determined to be -2.9 cm/GW at 78 GW/cm2, an
enhancement of nearly fourfold in comparison with that of pure PbS quantum dots
(QDs). The enhancement is attributed to excitation of surface plasmon by
resonant energy transfer between PbS QDs and Au nanoparticles through Auger
recombination.Comment: 14 pages, 3 figures. Accepted in Appl. Phys. Lett. (2008
Luminescence in sulfides : a rich history and a bright future
Sulfide-based luminescent materials have attracted a lot of attention for a wide range of photo-, cathodo- and electroluminescent applications. Upon doping with Ce3+ and Eu2+, the luminescence can be varied over the entire visible region by appropriately choosing the composition of the sulfide host. Main application areas are flat panel displays based on thin film electroluminescence, field emission displays and ZnS-based powder electroluminescence for backlights. For these applications, special attention is given to BaAl2S4:Eu, ZnS:Mn and ZnS:Cu. Recently, sulfide materials have regained interest due to their ability (in contrast to oxide materials) to provide a broad band, Eu2+-based red emission for use as a color conversion material in white-light emitting diodes (LEDs). The potential application of rare-earth doped binary alkaline-earth sulfides, like CaS and SrS, thiogallates, thioaluminates and thiosilicates as conversion phosphors is discussed. Finally, this review concludes with the size-dependent luminescence in intrinsic colloidal quantum dots like PbS and CdS, and with the luminescence in doped nanoparticles
Carrier multiplication between interacting nanocrystals for fostering silicon-based photovoltaics
Being a source of clean and renewable energy, the possibility to convert
solar radiation in electric current with high efficiency is one of the most
important topics of modern scientific research. Currently the exploitation of
interaction between nanocrystals seems to be a promising route to foster the
establishment of third generation photovoltaics. Here we adopt a fully
ab-initio scheme to estimate the role of nanoparticle interplay on the carrier
multiplication dynamics of interacting silicon nanocrystals. Energy and charge
transfer-based carrier multiplication events are studied as a function of
nanocrystal separation showing benefits induced by the wavefunction sharing
regime. We prove the relevance of these recombinative mechanisms for
photovoltaic applications in the case of silicon nanocrystals arranged in dense
arrays, quantifying at an atomistic scale which conditions maximize the
outcome.Comment: Supplementary materials are freely available onlin
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