Publications (71) View all
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Article: Trapping volume control in optical tweezers using cylindrical vector beams.
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ABSTRACT: We present the result of an investigation into the optical trapping of spherical microparticles using laser beams with a spatially inhomogeneous polarization direction [cylindrical vector beams (CVBs)]. We perform three-dimensional tracking of the Brownian fluctuations in the position of a trapped particle and extract the trap spring constants. We characterize the trap geometry by the aspect ratio of spring constants in the directions transverse and parallel to the beam propagation direction and evaluate this figure of merit as a function of polarization angle. We show that the additional degree of freedom present in CVBs allows us to control the optical trap strength and geometry by adjusting only the polarization of the trapping beam. Experimental results are compared with a theoretical model of optical trapping using CVBs derived from electromagnetic scattering theory in the T-matrix framework.Optics Letters 01/2013; 38(1):28-30. · 3.40 Impact Factor -
Article: Quantum plasmonics with quantum dot-metal nanoparticle molecules: influence of the Fano effect on photon statistics.
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ABSTRACT: We study theoretically the quantum optical properties of hybrid molecules composed of an individual quantum dot and a metallic nanoparticle. We calculate the resonance fluorescence of this composite system. Its incoherent part, arising from nonlinear quantum processes, is enhanced by more than 2 orders of magnitude as compared to that of the dot alone. The coupling between the two systems gives rise to a Fano interference effect which strongly influences the quantum statistical properties of the scattered photons: a small frequency shift of the incident light field may cause changes in the intensity correlation function of the scattered field of orders of magnitude. The system opens a good perspective for applications in active metamaterials and ultracompact single-photon devices.Physical Review Letters 12/2010; 105(26):263601. · 7.37 Impact Factor -
Article: Stratified dust grains in the interstellar medium – II. Time‐dependent interstellar extinction
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ABSTRACT: We consider a model of diffuse cloud dust in which carbon is deposited slowly on the surfaces of silicate cores. The solid carbon is also processed by the interstellar radiation so that its optical properties change with time. The computed interstellar extinction curves (ISECs) for this model evolve in time, lie close to the observed mean ISEC for substantial periods but generate at later times significant dispersions in the far-ultraviolet (for ISECs normalized in the visual). The requirement on the carbon budget is well within that available, while essentially all the available silicon must be in the silicate cores. The variety of observed ISECs may therefore be interpreted (at least, in part) as due to evolutionary changes in a time-dependent model of interstellar dust.Monthly Notices of the Royal Astronomical Society 07/2010; 408(1):535 - 541. · 4.90 Impact Factor -
Article: Brownian Motion of Graphene
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ABSTRACT: We study the Brownian motion (BM) of optically trapped graphene flakes. These orient orthogonal to the light polarization, due to the optical constants anisotropy. We explain the flake dynamics, measure force and torque constants and derive a full electromagnetic theory of optical trapping. The understanding of two dimensional BM paves the way to light-controlled manipulation and all-optical sorting of biological membranes and anisotropic macromolecules.06/2010; -
Article: Quantum Electrodynamics of Quantum Dot-Metal Nanoparticles Molecules
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ABSTRACT: We study theoretically the quantum optical properties of hybrid molecules composed of an individual quantum dot and a metallic nanoparticle. We calculate the resonance fluorescence of this hybrid system. Its incoherent part, the one arising from nonlinear quantum processes, results to be enhanced by more than two orders of magnitude as compared to that in the absence of the metallic nanoparticle. Scattering spectra at different excitation powers and nonperturbative calculations of intensity-field correlation functions show that this system can act as a nonlinear ultra-compact two-photon switch for incident photons, where the presence (or absence) of a single incident photon field is sufficient to allow (or prevent) the scattering of subsequent photons. We also find that a small frequency shift of the incident light field may cause changes in the intensity field correlation function of orders of magnitude. Comment: 15 pages, 4 figures04/2010;
