Search results for "electronics"
showing 10 items of 4340 documents
Blue luminescence in ZnO single crystals, nanopowders, ceramic
2007
The luminescence spectra and luminescence decay processes were studied in a ZnO single crystal, nanopowders and ceramic at liquid helium and room temperature under VUV synchrotron radiation as well as under pulsed laser excitation. The exciton-exciton and exciton-multiphonon processes were compared in different ZnO nanopowders (commercial powder, powders obtained by vaporization-condensation technique) and ceramic. The possibility of luminescence decay time modification by Al3+ doping was shown.
Influence of the excitation conditions on the emission behavior of carbon nanodot-based planar microcavities
2020
The authors investigate the influence of the pulse length as well as the repetition rate of the optical excitation on the emission behavior of carbon-nanodot-based planar microcavities.
Automatic tunable and reconfigurable fiberoptic microwave filters based on a broadband optical source sliced by uniform fiber Bragg gratings.
2002
We demonstrate an automatic tunable transversal notch filter based on uniform fiber Bragg gratings and a broadband optical source. High tunability can be performed by stretching the fiber with the gratings written in series. Also, high sidelobe supression can be achieved by introducing tunable attenuators in a parallel configuration of the gratings.
Room temperature polariton luminescence from a GaN∕AlGaN quantum well microcavity
2006
The authors report on the demonstration of strong light-matter coupling at room temperature using a crack-free UV microcavity containing GaN/AlGaN quantum wells (QWs). Lattice-matched AlInN/AlGaN distributed Bragg reflectors (DBRs) with a maximum peak reflectivity of 99.5% and SiO2/Si3N4 DBRs were used to form high finesse hybrid microcavities. State-of-the-art GaN/Al0.2Ga0.8N QWs emitting at 3.62 eV with a linewidth of 45 meV at 300 K were inserted in these structures. For a 3 lambda/2 microcavity containing six QWs, the interaction between cavity photons and QW excitons is sufficiently large to reach the strong coupling regime. A polariton luminescence is observed with a vacuum field Rabi…
Acoustically tunable photonic structures based on microcavity polaritons
2006
Abstract The interaction between surface acoustic waves (SAWs) with (Al,Ga)As microcavity polaritons results in the formation of a dynamic optical superlattice with folded light dispersion and energy stop bands when the lower polariton branch is predominantly of photonic character. For small detunings between the excitonic and optical cavity resonances, the SAW bleaches the polariton resonances through the efficient dissociation of the excitons by its piezoelectric field.
Entanglement control in hybrid optomechanical systems
2012
We demonstrate the control of entanglement in a hybrid optomechanical system comprising an optical cavity with a mechanical end-mirror and an intracavity Bose-Einstein condensate (BEC). Pulsed laser light (tuned within realistic experimental conditions) is shown to induce an almost sixfold increase of the atom-mirror entanglement and to be responsible for interesting dynamics between such mesoscopic systems. In order to assess the advantages offered by the proposed control technique, we compare the time-dependent dynamics of the system under constant pumping with the evolution due to the modulated laser light.
Ab initio calculations of PbTiO 3 /SrTiO 3 (001) heterostructures
2016
We performed ab initio calculations for the PbTiO3/SrTiO3 (001) heterostructures. For both PbO and TiO2-terminations of the PbTiO3 (001) thin film, augmented on the SrTiO3 (001) substrate, the magnitudes of atomic relaxations Δz increases as a function of the number of augmented monolayers. For both terminations of the augmented PbTiO3 (001) nanothin film, all upper, third and fifth monolayers are displaced inwards (Δz is negative), whereas all second, fourth and sixth monolayers are displaced outwards (Δz is positive). The B3PW calculated PbTiO3/SrTiO3 (001) heterostructure band gaps, independently from the number of augmented layers, are always smaller than the PbTiO3 and SrTiO3 bulk band…
Nanoparticles at fluid interfaces.
2017
Nanoparticles at fluid interfaces are becoming a central topic in colloid science studies. Unlike in the case of colloids in suspensions, the description of the forces determining the physical behavior of colloids at interfaces still represents an outstanding problem in the modern theory of colloidal interactions. These forces regulate the formation of complex two-dimensional structures, which can be exploited in a number of applications of technological interest; optical devices, catalysis, molecular electronics or emulsions stabilization. From a fundamental viewpoint and typical for colloidal systems, nanoparticles and microparticles at interfaces are ideal experimental and theoretical mo…
Epitaxy of thin films of the Heusler compound
2007
Abstract Epitaxial thin films of the highly spin polarized Heusler compound Co 2 Cr 0.6 Fe 0.4 Al are deposited by DC magnetron sputtering. It is shown by XRD and TEM investigations how the use of an Fe buffer layer on MgO(1 0 0) substrates supports the growth of highly ordered Co 2 Cr 0.6 Fe 0.4 Al at low deposition temperatures. The as-grown samples show a relatively large ordered magnetic moment of μ ≃ 3.0 μ B / f . u . providing evidence for a low level of disorder.
Band Alignments in InxGa1–xP/GaAs Heterostructures Investigated by Pressure Experiments
2000
6 páginas, 3 figuras.