Showing papers by "Guilhem Gallot published in 2009"
TL;DR: An extended Fano model is developed describing the Extraordinary Electromagnetic Transmission through arrays of subwavelength apertures, based on terahertz transmission measurements of arrays of various hole size and shapes, which gives access to a simple analytical description of EET.
Abstract: We developed an extended Fano model describing the Extraordinary Electromagnetic Transmission (EET) through arrays of subwavelength apertures, based on terahertz transmission measurements of arrays of various hole size and shapes. Considering a frequency-dependent coupling between resonant and non-resonant pathways, this model gives access to a simple analytical description of EET, provides good agreement with experimental data, and offers new parameters describing the influence of the hole size and shape on the transmitted signal.
10 citations
07 May 2009
TL;DR: A wideband spectral diagnostic system based on dispersion property of the Zinc Selenide prism, a crystalline material highly dispersive in the near-to-far infrared spectral range, has been studied and developed for the laser wakefield acceleration experiment at LOA for the measurement of few femto-seconds long electron beam as discussed by the authors.
Abstract: A wide-band spectral diagnostic system based on dispersion property of the Zinc Selenide prism, a crystalline material highly dispersive in the near-to-far infrared spectral range, has been studied and developed for the laser wakefield acceleration experiment at LOA for the measurement of few femto-seconds long electron beam. The extensive PIC simulation studies of the colliding-beam LWFA have shown very short electron beam duration of less than 10 femtoseconds. The prism spectrometer diagnostic with highly sensitive Mercury Cadmium Telluride infrared detector and the diffraction-grating spectrometer with a high-resolution imaging visible camera together have the spectral range coverage and resolution capable of detecting ultra-short Coherent Transition Radiation (CTR) generated by interaction of bunch charges with a 100 microns thickness aluminum foil. The beam profile of asymmetric shape then could be extracted from the CTR spectrum by inverse Fourier transformation with Kramers-Kronig relation. The diagnostic system has been tested and calibrated for characterization of blackbody source spectrum and spectral responsivity. The measurement of electron beam duration of few femtoseconds has yet been convincingly shown with high resolution, and the measurements of this kind have important implication in understanding and subsequent successful operation of the future FEL light source with a highly mono-energetic LWFA beam source.
2 citations
10 Nov 2009
TL;DR: In this article, a simple and reliable method for measuring beam waists in TDS is presented based on the successive diffraction by an opaque disk followed by a small circular aperture, which is not directly applicable to time domain spectroscopy (TDS).
Abstract: Classical variable aperture masking method is not directly applicable to Time Domain Spectroscopy (TDS) experiments. Here, we present a simple and reliable method for measuring beam waists in TDS. It is based on the successive diffraction by an opaque disk followed by a small circular aperture.
10 Nov 2009
TL;DR: In this article, the authors investigate changes in the extraordinary electromagnetic transmission through subwavelength hole arrays versus hole depth and find an exponential decrease of extraordinary transmission due to the effective skin depth of sub-wavelength holes arrays.
Abstract: We experimentally investigate changes in the extraordinary electromagnetic transmission through subwavelength hole arrays versus hole depth. We find an exponential decrease of extraordinary transmission due to the effective skin depth of subwavelength hole arrays.