Métamatériaux à biréfringence extraordinaire pour le THz, le micro-onde et le visible

National audience&nbsp

Conception de lames demi-onde ultra-minces pour les gammes micro-onde et optique

National audience&nbsp

Exalted transmission through a periodic structure of metallic C-shaped apertures sub-wavelength

International audience<span style="left: 122.6px; top: 411.588px; font-size: 20px; font-family: serif; transform: scaleX(1.05058);"&gtThe objective of this work is to study the properties of the t</span&gt<span style="left: 620.8px; top: 411.588px; font-size: 20px; font-family: serif; transform: scaleX(1.02406);"&gtransmission through a periodic </span&gt<span style="left: 118px; top: 434.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00073);"&gtarray</span&gt<span style="left: 164.2px; top: 434.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00926);"&gtof the sub</span&gt<span style="left: 243.8px; top: 434.588px; font-size: 20px; font-family: serif;"&gt-</span&gt<span style="left: 250.6px; top: 434.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00027);"&gtwavelength</span&gt<span style="left: 348.2px; top: 434.588px; font-size: 20px; font-family: serif;"&gtC</span&gt<span style="left: 361.6px; top: 434.588px; font-size: 20px; font-family: serif;"&gt-</span&gt<span style="left: 368.2px; top: 434.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00027);"&gtshaped</span&gt<span style="left: 429px; top: 434.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00379);"&gtapertures engraved</span&gt<span style="left: 586.4px; top: 434.588px; font-size: 20px; font-family: serif; transform: scaleX(1.01037);"&gtin a metal film</span&gt<span style="left: 710.2px; top: 434.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00306);"&gt(see figure</span&gt<span style="left: 800.6px; top: 434.588px; font-size: 20px; font-family: serif;"&gt1</span&gt<span style="left: 810.6px; top: 434.588px; font-size: 20px; font-family: serif;"&gt-</span&gt<span style="left: 817.4px; top: 434.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00097);"&gta)</span&gt<span style="left: 832.8px; top: 434.588px; font-size: 20px; font-family: serif; transform: scaleX(1);"&gt. </span&gt<span style="left: 842.8px; top: 434.588px; font-size: 20px; font-family: serif; transform: scaleX(1);"&gtThe </span&gt<span style="left: 118px; top: 457.588px; font-size: 20px; font-family: serif; transform: scaleX(1.05196);"&gtnumerical study of this type of structure is realized by the Finite Difference Time Domain </span&gt<span style="left: 118px; top: 480.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00816);"&gt(FDTD), which is a house code developed </span&gt<span style="left: 464.4px; top: 480.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00853);"&gtwithin our team. The annular C</span&gt<span style="left: 717.6px; top: 480.588px; font-size: 20px; font-family: serif;"&gt-</span&gt<span style="left: 724.4px; top: 480.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00497);"&gtshaped structure is </span&gt<span style="left: 118px; top: 503.588px; font-size: 20px; font-family: serif; transform: scaleX(0.978441);"&gtcompact and has the advantage of having the fundamental mode TE</span&gt<span style="left: 698.194px; top: 512.062px; font-size: 13.4px; font-family: serif; transform: scaleX(1);"&gt10</span&gt<span style="left: 720.4px; top: 503.588px; font-size: 20px; font-family: serif; transform: scaleX(0.975432);"&gt(see figure 1</span&gt<span style="left: 827.6px; top: 503.588px; font-size: 20px; font-family: serif;"&gt-</span&gt<span style="left: 834.2px; top: 503.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00046);"&gtb) </span&gt<span style="left: 859.8px; top: 503.588px; font-size: 20px; font-family: serif; transform: scaleX(0.988417);"&gtat </span&gt<span style="left: 118px; top: 526.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00049);"&gtwavelengths much greater than those of the fundamental modes of the other guiding structures </span&gt<span style="left: 118px; top: 549.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00773);"&gtsuch as the coaxial cavity</span&gt<span style="left: 328.8px; top: 549.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00901);"&gt[1], </span&gt<span style="left: 362.8px; top: 549.588px; font-size: 20px; font-family: serif;"&gtr</span&gt<span style="left: 369.4px; top: 549.588px; font-size: 20px; font-family: serif; transform: scaleX(1.0006);"&gtectangular</span&gt<span style="left: 458px; top: 549.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00086);"&gt[2]</span&gt<span style="left: 481.6px; top: 549.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00231);"&gt, etc. </span&gt<span style="left: 525.4px; top: 549.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00556);"&gtand while moving away from Rayleigh and </span&gt<span style="left: 118px; top: 572.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00368);"&gtplasmonic anomalies. </span&gt<span style="left: 307.6px; top: 572.588px; font-size: 20px; font-family: serif; transform: scaleX(1.01057);"&gtIn addition to its compactness, this structure provides a breaking </span&gt<span style="left: 118px; top: 595.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00698);"&gtsymmetry and therefore it is promising for the realization of metamaterials exhibiting original </span&gt<span style="left: 118px; top: 618.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00027);"&gtprop</span&gt<span style="left: 154.6px; top: 618.588px; font-size: 20px; font-family: serif; transform: scaleX(0.982947);"&gterties such as negative refractive index or artificial anisotropy [</span&gt<span style="left: 696px; top: 618.588px; font-size: 20px; font-family: serif; transform: scaleX(1.0006);"&gt2]</span&gt<span style="left: 721.8px; top: 618.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00039);"&gtwit</span&gt<span style="left: 747.4px; top: 618.588px; font-size: 20px; font-family: serif; transform: scaleX(0.992953);"&gth extraordinary </span&gt<span style="left: 118px; top: 642.588px; font-size: 20px; font-family: serif; transform: scaleX(0.998477);"&gtbirefringence (</span&gt<span style="left: 236.2px; top: 645.41px; font-size: 20px; font-family: sans-serif;"&gt∆</span&gt<span style="left: 247.4px; top: 642.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00008);"&gtn= 0.75 </span&gt<span style="left: 313.6px; top: 642.588px; font-size: 20px; font-family: serif;"&gt[</span&gt<span style="left: 320.6px; top: 642.588px; font-size: 20px; font-family: serif;"&gt3</span&gt<span style="left: 330.6px; top: 642.588px; font-size: 20px; font-family: serif; transform: scaleX(1.00109);"&gt])</span&g

Numerical study of an efficient light focusing nano-coupler based on C-shaped waveguides

International audienceWe present an FDTD simulation study of a new design of light focusing nano-coupler consisting of a tapered succession of C-shaped silver waveguides. Its operation is based on the use of the fundamental guided mode <span class="mathjax-tex"&gt<span class="MathJax_Preview" style=""&gt</span&gt<span class="MathJax" id="MathJax-Element-1-Frame" tabindex="0" style="position: relative;" data-mathml="<math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt<mi&gtT</mi&gt<msub&gt<mi&gtE</mi&gt<mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt<mn&gt10</mn&gt</mrow&gt</msub&gt</math&gt" role="presentation"&gt<nobr aria-hidden="true"&gt<span class="math" id="MathJax-Span-1" style="width: 2.455em; display: inline-block;"&gt<span style="display: inline-block; position: relative; width: 2.202em; height: 0px; font-size: 111%;"&gt<span style="position: absolute; clip: rect(1.422em, 1002.2em, 2.568em, -1000em); top: -2.252em; left: 0em;"&gt<span class="mrow" id="MathJax-Span-2"&gt<span class="mi" id="MathJax-Span-3" style="font-family: MathJax_Math; font-style: italic;"&gtT<span style="display: inline-block; overflow: hidden; height: 1px; width: 0.12em;"&gt</span&gt</span&gt<span class="msubsup" id="MathJax-Span-4"&gt<span style="display: inline-block; position: relative; width: 1.52em; height: 0px;"&gt<span style="position: absolute; clip: rect(3.174em, 1000.76em, 4.154em, -1000em); top: -4.004em; left: 0em;"&gt<span class="mi" id="MathJax-Span-5" style="font-family: MathJax_Math; font-style: italic;"&gtE<span style="display: inline-block; overflow: hidden; height: 1px; width: 0.026em;"&gt</span&gt</span&gt<span style="display: inline-block; width: 0px; height: 4.004em;"&gt</span&gt</span&gt<span style="position: absolute; top: -3.854em; left: 0.738em;"&gt<span class="texatom" id="MathJax-Span-6"&gt<span class="mrow" id="MathJax-Span-7"&gt<span class="mn" id="MathJax-Span-8" style="font-size: 70.7%; font-family: MathJax_Main;"&gt10</span&gt</span&gt</span&gt<span style="display: inline-block; width: 0px; height: 4.004em;"&gt</span&gt</span&gt</span&gt</span&gt</span&gt<span style="display: inline-block; width: 0px; height: 2.252em;"&gt</span&gt</span&gt</span&gt<span style="display: inline-block; overflow: hidden; vertical-align: -0.239em; border-left: 0px solid; width: 0px; height: 1.05em;"&gt</span&gt</span&gt</nobr&gt</span&gt</span&gt<span class="mathjax-tex"&gt</span&gt. Thanks to the optimization of the structural design parameters, we have demonstrated numerically that this compact coupler enables a sub-wavelength light focusing with a transmission coefficient of 65% and a coupling efficiency of 77% that have higher values than the optimized designs reported in the literature. We also show that our structure is an efficient functional coupler at multiple wavelengths when used in a periodic grating as well as an isolated device. This could pave the way for the development of a new generation of metamaterials for guidance and detection applications

Half-wave plate based on a birefringent metamaterial in the visible range

International audienceIn this paper, a half-wave plate (HWP) based on a birefringent metamaterial is numerically designed to operate in the visible range. The proposed structure consists of an array of double-pattern perpendicular rectangular apertures (RAA) engraved into opaque silver film deposited on a glass substrate. One of the apertures is glass filled. The operating principle is based on the excitation and the propagation of one guided mode inside each aperture but with different effective indices. After transmission, a phase difference is obtained between the two transverse components, which value depends mainly on the metal thickness. We have investigated the simplest configuration using a homemade code based on the finite difference time domain method to design a half-wave plate with optimized efficiency resulting in transmission coefficient of more than 60% together with a birefringence of 2.1 at an operation wavelength of 737nm.<span class="math"&gt<span class="MathJax_Preview" style=""&gt</span&gt<span style="font-size: 90%; display: inline-block; position: relative;" class="MathJax_SVG" id="MathJax-Element-1-Frame" tabindex="0" data-mathml="<math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt<mrow is=&quot;true&quot;&gt<mn is=&quot;true&quot;&gt737</mn&gt<mspace class=&quot;nbsp&quot; width=&quot;1em&quot; is=&quot;true&quot; /&gt<mi is=&quot;true&quot; mathvariant=&quot;normal&quot;&gtnm</mi&gt</mrow&gt</math&gt" role="presentation"&gt<svg xmlns:xlink="http://www.w3.org/1999/xlink" width="9.425ex" height="1.972ex" style="vertical-align: -0.25ex;" viewBox="0 -741.6 4058.2 849.3" aria-hidden="true"&gt<g stroke="currentColor" fill="currentColor" stroke-width="0" transform="matrix(1 0 0 -1 0 0)"&gt<g&gt<g&gt<use xlink:href="https://www.sciencedirect.com/science/article/abs/pii/S0030401821000547?via%3Dihub#MJMAIN-33" x="500" y="0"&gt</use&gt<use xlink:href="https://www.sciencedirect.com/science/article/abs/pii/S0030401821000547?via%3Dihub#MJMAIN-37" x="1001" y="0"&gt</use&gt</g&gt</g&gt</g&gt</svg&gt</span&gt</span&gtThis kind of anisotropic metasurfaces promises a wide range of applications in integrated photonics

Implementation of the FDTD method in cylindrical coordinates for dispersive materials: Modal study of C-shaped nano-waveguides

International audienceThe objective of this work is to develop a code based on the finite difference time domain method in cylindrical coordinates (CC-FDTD) that integrates the Drude Critical Points model (DCP) and to apply it in the study of a metallic C-shaped waveguide (CSWG). The integrated dispersion model allows an accurate description of noble metals in the optical range and working in cylindrical coordinates is necessary to bypass the staircase effect induced by a Cartesian mesh especially in the case of curved geometrical forms. The CC-FDTD code developed as a part of this work is more general than the Body-Of-Revolution-FDTD algorithm that can only handle structures exhibiting a complete cylindrical symmetry. A N-order CC-FDTD code is then derived and used to perform a parametric study of an infinitly-long CSWG for nano-optic applications. Propagation losses and dispersion diagrams are given for different geometrical parameters

Conception par FDTD d’une lame demi onde dans la gamme optique à base de métamatériau biréfrignent

International audience<span style="left: 118.18px; top: 407.223px; font-size: 15px; font-family: serif; transform: scaleX(1.00097);"&gtDans ce travail, nous avons étudié un réseau périodique sublongueur d'onde composé de</span&gt<span style="left: 647.98px; top: 407.223px; font-size: 15px; font-family: serif; transform: scaleX(0.999398);"&gt deux ouvertures rectangulaire et </span&gt<span style="left: 118.18px; top: 424.623px; font-size: 15px; font-family: serif; transform: scaleX(0.997207);"&gtcoaxiale </span&gt<span style="left: 171.775px; top: 424.623px; font-size: 15px; font-family: serif; transform: scaleX(1.00172);"&gtgravées dans un film en argent</span&gt<span style="left: 355.57px; top: 424.623px; font-size: 15px; font-family: serif; transform: scaleX(1.004);"&gt dans le but de</span&gt<span style="left: 442.36px; top: 424.623px; font-size: 15px; font-family: serif; transform: scaleX(0.996076);"&gt concevoir des </span&gt<span style="left: 532.555px; top: 424.623px; font-size: 15px; font-family: serif; transform: scaleX(0.98822);"&gtlames</span&gt<span style="left: 567.355px; top: 424.623px; font-size: 15px; font-family: serif; transform: scaleX(1.00095);"&gt biréfringentes dans le domaine optique. Cette </span&gt<span style="left: 118.15px; top: 441.828px; font-size: 15px; font-family: serif; transform: scaleX(1.00034);"&gtétude a été réalis</span&gt<span style="left: 218.545px; top: 441.828px; font-size: 15px; font-family: serif; transform: scaleX(0.994135);"&gtée </span&gt<span style="left: 235.54px; top: 441.828px; font-size: 15px; font-family: serif; transform: scaleX(1.00043);"&gtà l'aide d'un code maison FDTD où la dispersion du métal est décrite par le modèl</span&gt<span style="left: 727.135px; top: 441.828px; font-size: 15px; font-family: serif; transform: scaleX(1.006);"&gte de Drude</span&gt<span style="left: 793.135px; top: 441.828px; font-size: 15px; font-family: serif; transform: scaleX(0.997938);"&gt à deux </span&gt<span style="left: 118.135px; top: 459.033px; font-size: 15px; font-family: serif; transform: scaleX(1.00025);"&gtpoints critiques (DCP). La particularité du mode TEM de la cavité coaxiale, qui peut être excité à des longueurs d'onde él</span&gt<span style="left: 846.73px; top: 459.033px; font-size: 15px; font-family: serif; transform: scaleX(0.990129);"&gte-</span&gt<span style="left: 118.135px; top: 476.238px; font-size: 15px; font-family: serif; transform: scaleX(1.00027);"&gtvées, a permis de concevoir une plaque demi</span&gt<span style="left: 387.13px; top: 476.238px; font-size: 15px; font-family: serif; transform: scaleX(1.00686);"&gt-onde </span&gt<span style="left: 425.125px; top: 476.238px; font-size: 15px; font-family: serif; transform: scaleX(1.0009);"&gtdans le domaine optique</span&g

Optimization of the transmission of the AAA structure through TEM mode

International audience<span style="left: 252.601px; top: 327.209px; font-size: 16.6px; font-family: serif; transform: scaleX(0.971116);"&gtThe present work is devoted to the transmission of the real metal Annular Aperture </span&gt<span style="left: 178.2px; top: 346.415px; font-size: 16.6px; font-family: serif; transform: scaleX(0.969667);"&gtArray (AAA) through the TEM mode. The used FDTD code that we previously developed, can </span&gt<span style="left: 178.2px; top: 365.622px; font-size: 16.6px; font-family: serif; transform: scaleX(0.999485);"&gtsimulates structures excited by oblique incidence. We have shown that the inclination of the </span&gt<span style="left: 178.216px; top: 384.828px; font-size: 16.6px; font-family: serif; transform: scaleX(1.01644);"&gtapertures of these structures allowed exciting the TEM mode in normal incidence. This inclination </span&gt<span style="left: 178.233px; top: 404.034px; font-size: 16.6px; font-family: serif; transform: scaleX(1.03637);"&gtalso induced the displacement of the TEM peak towards the red with greater intensity. The AAA </span&gt<span style="left: 178.233px; top: 423.041px; font-size: 16.6px; font-family: serif; transform: scaleX(0.984123);"&gtclassical structure, with an extension of the coax</span&gt<span style="left: 515.014px; top: 423.041px; font-size: 16.6px; font-family: serif; transform: scaleX(0.959493);"&gt core and excited at oblique incidence, allowed</span&gt<span style="left: 178.249px; top: 442.247px; font-size: 16.6px; font-family: serif; transform: scaleX(0.946629);"&gtredshift of the TEM peak. This shift is a function of the imposed elongation on both sides of the </span&gt<span style="left: 178.249px; top: 461.453px; font-size: 16.6px; font-family: serif; transform: scaleX(1.00546);"&gtcoax core</span&g

Design of a half-wave plate based on metamaterials in the optical range

International audience<span style="left: 239.827px; top: 377.189px; font-size: 18.4px; font-family: serif; transform: scaleX(0.970794);"&gt We present in this contribution the design of metamaterial-based half-wave </span&gt<span style="left: 165.234px; top: 398.184px; font-size: 18.4px; font-family: serif; transform: scaleX(0.940475);"&gtplate operating in the optical range. This na</span&gt<span style="left: 496.206px; top: 398.184px; font-size: 18.4px; font-family: serif; transform: scaleX(0.948033);"&gtnostructure consists on a bi-periodic grating </span&gt<span style="left: 165.234px; top: 419.38px; font-size: 18.4px; font-family: serif; transform: scaleX(0.944773);"&gtcombining one annular aperture with one C-shaped aperture both engraved into a metal </span&gt<span style="left: 165.234px; top: 440.428px; font-size: 18.4px; font-family: serif; transform: scaleX(1.01542);"&gtlayer. The artificial anisotropy is induced by the geometry of the structure that presents a </span&gt<span style="left: 165.234px; top: 461.627px; font-size: 18.4px; font-family: serif; transform: scaleX(1.00898);"&gtrupture of symmetry, allowing the control of </span&gt<span style="left: 500.051px; top: 461.627px; font-size: 18.4px; font-family: serif; transform: scaleX(1.00415);"&gtthe polarization state of the light transmitted </span&gt<span style="left: 165.234px; top: 482.619px; font-size: 18.4px; font-family: serif; transform: scaleX(1.00903);"&gtthrough these plates. The FDTD numerical results show high performances: transmission </span&gt<span style="left: 165.234px; top: 503.816px; font-size: 18.4px; font-family: serif; transform: scaleX(0.997116);"&gtof around 60% together with an artificial birefringence </span&gt<span style="left: 571.524px; top: 503.814px; font-size: 18.4px; font-family: sans-serif; transform: scaleX(0.957006);"&gtof Δn=</span&gt<span style="left: 622.915px; top: 503.816px; font-size: 18.4px; font-family: serif; transform: scaleX(0.990311);"&gt 2.6. </span&g