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Search Results: 1 - 10 of 7637 matches for " Philippe Lalanne "
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Theoretical treatment of the interaction between two-level atoms and periodic waveguides
Xiaorun Zang,Philippe Lalanne
Physics , 2015, DOI: 10.1364/OL.40.003869
Abstract: Light transport in periodic waveguides coupled to a two-level atom is investigated. By using optical Bloch equations and a photonic modal formalism, we derive semi-analytical expressions for the scattering matrix of one atom trapped in a periodic waveguide. The derivation is general, as the expressions hold for any periodic photonic or plasmonic waveguides. It provides a basic building block to study collective effects arising from photon-mediated multi-atom interactions in periodic waveguides.
Waves on subwavelength metallic surfaces: a microscopic view point
Philippe Lalanne,Haitao Liu
Physics , 2012,
Abstract: The electromagnetic properties of subwavelength metallic surfaces are due to two kinds of elementary distinct waves, the famous surface plasmon polariton and the quasi-cylindrical wave, which are both scattered by the subwavelength indentations as they propagate on the metal. The ab-initio microscopic description of the electromagnetic properties starting from the sole knowledge of the elementary waves launched in between the indentation has a long history in grating theories. We review the evolution of the ideas and the fundamental principles that govern these waves and their impacts. For the sake of illustration, the emblematic case of a metal surface perforated by a subwavelength-hole array, which exhibits remarkable transmission properties, is taken to illustrate our purpose.
Light emission in nanogaps: overcoming quenching
Jianji Yang,Rémi Faggiani,Philippe Lalanne
Physics , 2015, DOI: 10.1039/C5NH00059A
Abstract: Very large spontaneous-emission-rate enhancements (~1000) are obtained for quantum emitters coupled with tiny plasmonic resonance, especially when emitters are placed in the mouth of nanogaps formed by metal nanoparticles that are nearly in contact. This fundamental effect of light emission at subwavelength scales is well documented and understood as resulting from the smallness of nanogap modes. In contrasts, it is much less obvious to figure out whether the radiation efficiency is high in these gaps, or if the emission is quenched by metal absorption especially for tiny gaps a few nanometers wide; the whole literature only contains scattered electromagnetic calculations on the subject, which suggest that absorption and quenching can be kept at a small level despite the emitter proximity to metal. Thus through analytical derivations in the limit of small gap thickness, it is our objective to clarify why quantum emitters in nanogap antennas offer good efficiencies, what are the circumstances in which high efficiency is obtained, and whether there exists an upper bound for the maximum efficiency achievable.
Simple analytical expression for the peak-frequency shifts of plasmonic resonances for sensing
Jianji Yang,Harald Giessen,Philippe Lalanne
Physics , 2015, DOI: 10.1021/acs.nanolett.5b00771
Abstract: We derive a closed-form expression that accurately predicts the peak frequency-shift and broadening induced by tiny perturbations of plasmonic nanoresonators without critically relying on repeated electrodynamic simulations of the spectral response of nanoresonator for various locations, sizes or shapes of the perturbing objects. The force of the present approach, in comparison with other approaches of the same kind, is that the derivation is supported by a mathematical formalism based on a rigorous normalization of the resonance modes of nanoresonators consisting of lossy and dispersive materials. Accordingly, accurate predictions are obtained for a large range of nanoparticle shapes and sizes, used in various plasmonic nanosensors, even beyond the quasistatic limit. The expression gives quantitative insight, and combined with an open-source code, provides accurate and fast predictions that are ideally suited for preliminary designs or for interpretation of experimental data. It is also valid for photonic resonators with large mode volumes.
Quenching, plasmonic and radiative decays in nanogap emitting devices
Remi Faggiani,Jianji Yang,Philippe Lalanne
Physics , 2015,
Abstract: By placing a quantum emitter in the mouths of nanogaps consisting of two metal nanoparticles nearly into contact, significant increases in emission rate are obtained. This mechanism is central in the design of modern plasmonic nanoantennas. However, due to the lack of general knowledge on the balance between the different decay rates in nanogaps (emission, quenching, and metal absorption), the design of light-emitting devices based on nanogaps is performed in a rather hazardous fashion; general intuitive recipes do not presently exist. With accurate and simple closed-form expressions for the quenching rate and the decay rate into gap plasmons, we provide a comprehensive analysis of nanogap light emitting devices in the limit of small gap thickness. We disclose that the total decay rate in gap plasmons can largely overcome quenching for specifically selected metallic and insulator materials, regardless of the gap size. To confront these theoretical predictions, we provide a comprehensive numerical analysis of nanocube-type antennas in the limit of small gap thickness and further provide upper bounds for the photon-radiation efficiency.
On the attenuation coefficient of monomode periodic waveguides
Alexandre Baron,Simon Mazoyer,Wojciech Smigaj,Philippe Lalanne
Physics , 2011, DOI: 10.1103/PhysRevLett.107.153901
Abstract: It is widely accepted that, on ensemble average, the transmission T of guided modes decays exponentially with the waveguide length L due to small imperfections, leading to the important figure of merit defined as the attenuation-rate coefficient alpha = -/L. In this letter, we evidence that the exponential-damping law is not valid in general for periodic monomode waveguides, especially as the group velocity decreases. This result that contradicts common beliefs and experimental practices aiming at measuring alpha is supported by a theoretical study of light transport in the limit of very small imperfections, and by numerical results obtained for two waveguide geometries that offer contrasted damping behaviours.
Proposal for compact solid-state III-V single-plasmon sources
Choon How Gan,Jean-Paul Hugonin,Philippe Lalanne
Physics , 2012,
Abstract: We propose a compact single-plasmon source operating at near-infrared wavelengths on an integrated III-V semiconductor platform, with a thin ridge waveguide serving as the plasmon channel. By attaching an ultra-small cavity to the channel, it is shown that both the plasmon generation efficiency ({\beta}) and the spontaneous-decay rate into the channel can be significantly enhanced. An analytical model derived with the Lorentz reciprocity theorem captures the main physics involved in the design of the source and yields results in good agreement with fully-vectorial simulations of the device. At resonance, it is predicted that the ultra-small cavity increases the {\beta}-factor by 70% and boosts the spontaneous decay rate by a factor 20. The proposed design could pave the way towards integrated and scalable plasmonic quantum networks. Comparison of the present design with other fully-dielectric competing approaches is addressed.
Near-to-far field transformations for radiative and guided waves
Jianji Yang,Jean-Paul Hugonin,Philippe Lalanne
Physics , 2015,
Abstract: Light emitters or scatterers embedded in stratified media may couple energy to both free space and guided modes of the stratified structure. For a thorough analysis of such structures, it is important to evaluate the angular intensity distribution of both the free-space-propagative and guided waves. In this work, we propose an original method based on Lorentz-reciprocity theorem and on the computation of the near-field around the emitters or scatterers, to efficiently calculate the free-space and guided radiation diagrams with a high accuracy. We also provide an open-source code that may be used with virtually any Maxwells solver. The numerical tool may help to engineer various devices, such as light-emitting diodes or nanoantennas to achieve directional and efficient radiative spontaneous decays in free space and guided optics.
Measuring the spatial extent of individual localized photonic states
Marko Spasenovic,Daryl M. Beggs,Philippe Lalanne,Thomas F. Krauss,L.,Kuipers
Physics , 2011, DOI: 10.1103/PhysRevB.86.155153
Abstract: We measure the spatial extent of individual localized photonic states in a slow-light photonic crystal waveguide. The size of the states is measured by perturbing each state individually through a local electromagnetic interaction with a near-field probe. We find localized states which are not observed in transmission and show that these states are shorter than the waveguide. We also directly obtain near-field measurements of the participation ratio, from which the size of the states can be derived, in quantitative agreement with the size measured with the perturbation method.
Genre et jeunesse dans l'antiquité
Sophie Lalanne
Genre & Histoire , 2009,
Abstract: Généralités Bourdieu P. et Passeron J.-C., La reproduction. Eléments pour une théorie du système d’enseignement, Paris, Editions de Minuit, 1970.Bourdieu P., La jeunesse n’est qu’un mot , dans Questions de sociologie, Paris, Minuit, 1981. Bourdieu P., Les rites comme actes d’institution , dans Les rites de passage aujourd’hui, P. Centlivres et J. Hainard dir., Lausanne, L’age d’homme, 1986, p. 206-215.Bourdieu P., La domination masculine, Paris, Seuil, 1998.Duby G., Au XIIe siècle : l...
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