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Search Results: 1 - 10 of 198 matches for " Martial Ducloy "
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The laser, from yesterday (1960) to tomorrow
Ducloy Martial
Europhysics News , 2011, DOI: 10.1051/epn/2011102
Abstract:
Spectroscopy in Extremely Thin Vapor Cells : Sensitivity Issues
Martial Ducloy,Daniel Bloch
Physics , 2005,
Abstract: This communication focuses on sensitivity issues - a long-time concern of J. Hall- in the spectroscopic analysis of Extremely Thin Cell of dilute vapor. With these small and often submicrometric slices of vapor, the most uncommon features are the relatively small number of interacting atoms, and the fact that essential results are already obtained in the frame of linear spectroscopy.
Atom-Wall interaction
Daniel Bloch,Martial Ducloy
Physics , 2005,
Abstract: This chapter deals with atom-wall interaction occurring in the "long-range" regime (typical distances: 1-1000 nm), when the electromagnetic fluctuations of an isolated atom are modified by the vicinity with a surface. Various regimes of interaction are discussed in an Introductory part, from Cavity Quantum ElectroDynamics modifications of the spontaneous emission, to Casimir effect, with emphasis on the atom-surface van der Waals interaction, characterized as a near-field interaction governed by a z-3 dependence. The major part of the Chapter focuses on the experimental measurements of this van der Waals interaction, reviewing various recent techniques, and insists upon optical techniques, and notably selective reflection spectroscopy which is particularly well-suited when excited atoms are considered. A review of various experiments illustrates the specific effects associated with a resonant coupling between the atomic excitation and surface modes, from van der Waals repulsion to surface-induced resonant transfer, and with anisotropy effects, including metastability transfer induced by a quadrupole contribution in the interaction. The effects of a thermal excitation of the surface -with a possible remote energy transfer to an atom-, and of interaction with nanobodies -which are intrinsically non planar- are notably discussed among the prospects.
A Tabulation and Critical Analysis of the Wavelength-Dependent Dielectric Image Coefficient for the Interaction Exerted by a Surface onto a Neighbouring Excited Atom
Solomon Saltiel,Daniel Bloch,Martial Ducloy
Physics , 2006, DOI: 10.1016/j.optcom.2006.03.034
Abstract: The near-field interaction of an atom with a dielectric surface is inversely proportional to the cube to the distance to the surface, and its coupling strength depends on a dielectric image coefficient. This coefficient, simply given in a pure electrostatic approach by (eps-1) / (eps+1) with eps the permittivity, is specific to the frequency of each of the various relevant atomic transition : it depends in a complex manner from the bulk material properties, and can exhibit resonances connected to the surface polariton modes. We list here the surface resonances for about a hundred of optical windows whose bulk properties are currently tabulated. The study concentrates on the infrared domain because it is the most relevant for atom-surface interaction. Aside from this tabulation, we discuss simple hints to estimate the position of surface resonances, and how uncertainties in the bulk data for the material dramatically affect the predictions for the image coefficient. We also evaluate the contribution of UV resonances of the material to the non resonant part of the image coefficient.
Theoretical study of dark resonances in micro-metric thin cells
Horacio Failache,Lorenzo Lenci,Arturo Lezama,Daniel Bloch,Martial Ducloy
Physics , 2007, DOI: 10.1103/PhysRevA.76.053826
Abstract: We investigate theoretically dark resonance spectroscopy for a dilute atomic vapor confined in a thin (micro-metric) cell. We identify the physical parameters characterizing the spectra and study their influence. We focus on a Hanle-type situation, with an optical irradiation under normal incidence and resonant with the atomic transition. The dark resonance spectrum is predicted to combine broad wings with a sharp maximum at line-center, that can be singled out when detecting a derivative of the dark resonance spectrum. This narrow signal derivative, shown to broaden only sub-linearly with the cell length, is a signature of the contribution of atoms slow enough to fly between the cell windows in a time as long as the characteristic ground state optical pumping time. We suggest that this dark resonance spectroscopy in micro-metric thin cells could be a suitable tool for probing the effective velocity distribution in the thin cell arising from the atomic desorption processes, and notably to identify the limiting factors affecting desorption under a grazing incidence.
Engineering of radiation of optically active molecules with chiral nano-meta-particles
Vasily V. Klimov,Dmitry V. Guzatov,Martial Ducloy
Physics , 2011, DOI: 10.1209/0295-5075/97/47004
Abstract: The radiation of optically active (chiral) molecule placed near chiral nanoparticle is investigated. The optimal conditions for engineering of radiation of optically active (chiral) molecules with the help of chiral nanoparticles are derived. It is shown that for this purpose, the substance of the chiral particle must have both \epsilon_and \mu_negative (double negative material (DNG)) or negative \mu_and positive \epsilon_(\mu_negative material (MNG)). Our results pave the way to an effective engineering of radiation of "left" and "right" molecules and to creating pure optical devices for separation of drugs enantiomers.
Magnetic field-induced mixing of hyperfine states of Cs 6 2^P_{3/2} level observed with a sub-micron vapor cell
Aram Papoyan,David Sarkisyan,Kaspars Blush,Marcis Auzinsh,Daniel Bloch,Martial Ducloy
Physics , 2003,
Abstract: The fluorescence spectra of a sub-micron atomic cesium vapor layer observable under resonant excitation on D2 line have been studied in the presence of an external magnetic field. Substantial changes in amplitudes and frequency positions of the individual (resolved) hyperfine transitions have been recorded in moderate magnetic fields (up to ~ 50 Gauss). These features are caused by mixing of the hyperfine states of the upper level resulting from comparable values of the hyperfine splitting of the 62^P_{3/2} manifold and Larmor frequencies of the magnetic sublevels. The results of simulation show a good agreement with the experimental spectra. Possible application of the results for high spatial resolution magnetometry is discussed.
Selective Reflection Spectroscopy on the UV Third Resonance Line of Cs : Simultaneous Probing of a van der Waals Atom-Surface Interaction Sensitive to Far IR Couplings and of Interatomic Collisions
Pedro Chaves De Souza Segundo,Ismahène Hamdi,Michèle Fichet,Daniel Bloch,Martial Ducloy
Physics , 2007, DOI: 10.1134/S1054660X07070134
Abstract: We report on the analysis of FM selective reflection experiments on the 6S1/2->8P3/2 transition of Cs at 388 nm, and on the measurement of the surface van der Waals interaction exerted by a sapphire interface on Cs(8P3/2). Various improvements in the systematic fitting of the experiments have permitted to supersede the major difficulty of a severe overlap of the hyperfine components, originating on the one hand in a relatively small natural structure, and on the other hand on a large pressure broadening imposed by the high atomic density needed for the observation of selective reflection on a weak transition. The strength of the van der Waals surface interaction is evaluated to be 73$\pm$10 kHz.$\mu$m3. An evaluation of the pressure shift of the transition is also provided as a by-product of the measurement. We finally discuss the significance of an apparent disagreement between the experimental measurement of the surface interaction, and the theoretical value calculated for an electromagnetic vacuum at a null temperature. The possible influence of the thermal excitation of the surface is evoked, because, the dominant contributions to the vW interaction for Cs(8P3/2) lie in the far infrared range.
Mapping of focused Laguerre-Gauss beams: The interplay between spin and orbital angular momentum and its dependence on detector characteristics
Vasily V. Klimov,Daniel Bloch,Martial Ducloy,Jose Roberto Rios Leite
Physics , 2012,
Abstract: We show that propagating optical fields bearing an axial symmetry are not truly hollow in spite of a null electric field on-axis. The result, obtained by general arguments based upon the vectorial nature of electromagnetic fields, is of particular significance in the situation of an extreme focusing, when the paraxial approximation no longer holds. The rapid spatial variations of fields with a "complicated" spatial structure are extensively analyzed in the general case and for a Laguerre-Gauss beam 2 as well, notably for beams bearing a |l| = 2 orbital angular momentum for which a magnetic field and a gradient of the electric field are present on-axis. We thus analyze the behavior of a atomic size light-detector, sensitive as well to quadrupole electric transitions and to magnetic dipole transitions, and apply it to the case of Laguerre-Gauss beam. We detail how the mapping of such a beam depends on the nature and on the specific orientation of the detector. We show also that the interplay of mixing of polarization and topological charge, respectively associated to spin and orbital momentum when the paraxial approximation holds, modifies the apparent size of the beam in the focal plane. This even leads to a breaking of the cylindrical symmetry in the case of a linearly polarized transverse electric field.
Dicke Coherent Narrowing in Two-Photon and Raman Spectroscopy of Thin Vapour Cells
Gabriel Dutier,Petko Todorov,Ismahène Hamdi,Isabelle Maurin,Solomon Saltiel,Daniel Bloch,Martial Ducloy
Physics , 2005, DOI: 10.1103/PhysRevA.72.040501
Abstract: The principle of coherent Dicke narrowing in a thin vapour cell, in which sub-Doppler spectral lineshapes are observed under a normal irradiation for a l/2 thickness, is generalized to two-photon spectroscopy. Only the sum of the two wave vectors must be normal to the cell, making the two-photon scheme highly versatile. A comparison is provided between the Dicke narrowing with copropagating fields, and the residual Doppler-broadening occurring with counterpropagating geometries. The experimental feasibility is discussed on the basis of a first observation of a two-photon resonance in a 300 nm-thick Cs cell. Extension to the Raman situation is finally considered.
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