Lozan O.,French National Center for Scientific Research |
Perrin M.,French National Center for Scientific Research |
Ea-Kim B.,CNRS Charles Fabry Laboratory |
Rampnoux J.M.,French National Center for Scientific Research |
And 2 more authors.
Physical Review Letters | Year: 2014
In this Letter, we study the heat dissipated at metal surfaces by the electromagnetic field scattered by isolated subwavelength apertures in metal screens. In contrast to the common belief that the intensity of waves created by local sources should decrease with the distance from the sources, we reveal that the dissipated heat at the surface remains constant over a broad spatial interval. This behavior that occurs for noble metals at near infrared wavelengths is observed with nonintrusive thermoreflectance measurements and is explained with an analytical model, which underlines the intricate role played by quasicylindrical waves in the phenomenon. Additionally, we show that, by monitoring the phase of the quasicylindrical waves, the total heat dissipated at the metal surface can be rendered substantially smaller than the heat dissipated by the launched plasmon. This interesting property offers an alternative to amplification for overcoming the loss issue in miniaturized plasmonic devices. © 2014 American Physical Society.
Nosal S.,ETH Zurich |
Soudais P.,Dassault Aviation |
Greffet J.-J.,CNRS Charles Fabry Laboratory
IEEE Transactions on Antennas and Propagation | Year: 2012
A surface integral equation modeling is described for complex doubly periodic structures. To avoid long computations of the slowly convergent pseudoperiodic Green's function, fictitious surfaces between translated unit cells are set in order to bound regions of the structure within the symmetry cell and use the free-space Green's function. The integral operators on top and bottom surfaces are computed with an algorithm originally used for planar frequency-selective surfaces. This approach uses a unique periodic PMCHWT formulation in all the regions, with two different kinds of Green's function. The method and its advantages are illustrated by two cases in the near-IR domain and in the radar domain. A frequency selective structure is studied, that shows a large flat-top bandwidth under oblique incidence and TM polarization. © 2006 IEEE.
Dubois A.,CNRS Charles Fabry Laboratory
AIP Conference Proceedings | Year: 2013
Full-field optical coherence microscopy (FF-OCM) is a recent optical technology based on low-coherence interference microscopy for semi-transparent sample imaging with ∼ 1 μm spatial resolution. FF-OCM has been successfully applied to three-dimensional imaging of various biological tissues at cellular-level resolution. The contrast of FF-OCM images results from the intensity of light backscattered by the sample microstructures. This contrast mechanism, based on refractive index changes, provides information on the internal architectural morphology of the sample. In this paper, we present a multimodal FF-OCM system, capable of measuring simultaneously the intensity, the power spectrum and the phase-retardation of light backscattered by the sample being imaged. Tomographic fluorescence-based images can also be produced by coupling to the FF-OCM set-up a fluorescence microscopy system with structured illumination. Fluorescence targeted probes can be used to identify molecular components of subcellular scattering structures. Compared to conventional FF-OCM, this multimodal system provides enhanced imaging contrasts at the price of a moderate increase in experimental complexity and cost. © 2013 AIP Publishing LLC.
Lahaye T.,Toulouse 1 University Capitole |
Lahaye T.,French National Center for Scientific Research |
Lahaye T.,CNRS Charles Fabry Laboratory
European Journal of Physics | Year: 2012
I describe how to obtain a rather good experimental determination of the eccentricity of the Earths orbit, as well as the obliquity of the Earths rotation axis, by measuring, over the course of a year, the elevation of the Sun as a function of time during a day. With a very simple instrument consisting of an elementary sundial, first-year students can carry out an appealing measurement programme, learn important concepts in experimental physics, see concrete applications of kinematics and changes of reference frames, and benefit from a hands-on introduction to astronomy. © 2012 IOP Publishing Ltd.
Anna G.,CNRS Charles Fabry Laboratory |
Goudail F.,CNRS Charles Fabry Laboratory |
Dolfi D.,Thales Alenia
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2012
In active polarization imaging, one frequently needs to be insensitive to noninformative spatial intensity fluctuations. We investigate a way of solving this issue with general state contrast (GSC) imaging. It consists in acquiring two scalar polarimetric images with optimized illumination and analysis polarization states, then forming a ratio. We propose a method for maximizing the discrimination ability between a target and a background in GSC images by determining the optimal illumination and analysis states. A further advantage of this approach is to provide an objective way of quantifying the performance improvement obtained by increasing the number of degrees of freedom of a GSC imager. The efficiency of this approach is demonstrated on simulated and real-world images. © 2012 Optical Society of America.