Laëtitita RAGUIN "Surface Coupled Phononic Resonators"

Travaux de thèse de Laëtitia RAGUIN : "Surface Coupled Phononic Resonators"

Abstract : In the field of Phononics, most of the works reported up to now investigate the collective behaviour of periodic or aperiodic structures in order to control the propagation of elastic waves. In this thesis work, we propose to focus on the individual character of surface-coupled mechanical resonators with the aim to control and manipulate vibrations at the micron-scale. We investigate numerically and experimentally the coupling mechanisms involved between surface acoustic waves propagating on a substrate surface and mechanical modes of sub-wavelength phononic microresonators. Experimental investigations are conducted on isolated resonators and on pairs of neighboring resonators. The microresonator motion is measured using a laser scanning heterodyne interferometer which allows obtaining the frequency response and observing the vectorial behaviour of the elastic field both in the resonator and at the substrate surface.
In the first part of this thesis work, we demonstrate the possibility to excite the first flexural natural mode of a resonator with surface acoustic waves. Then, the reported investigations reveal the existence of two coupling regimes in pairs of resonating pillars, depending on the separation distance between two resonators: an evanescent coupling regime, much reminiscent of what can be observed in a plasmonic dimer, and a classical mechanical coupling. Measurements performed at the substrate surface also highlight the interaction through the surface between the resonators.
The obtained results prove that it is possible to control the elastic energy distribution at a deep sub-wavelength scale with isolated resonators, and reciprocally, that mechanical resonator systems can be manipulated by propagating surface acoustic waves, hence opening prospects for the dynamic and coherent control of mechanical vibrations at the micron-scale.

Jury Composition :

Abdelkrim KHELIF, Directeur de Recherche, Université Bourgogne - Franche-Comté, Directeur de thèse

Arnaud TOURIN, Professeur, Ecole supérieure de physique et de chimie industrielles de la ville de Paris, Rapporteur

Pierre VERLOT, Assistant Professeur, University of Nottingham, Rapporteur

Daniel LANZILLOTTI-KIMURA, Chargé de recherche, Centre de Nanosciences et de Nanotechnologies (C2N), Université Paris-Saclay, Examinateur

Romain FLEURY, Assistant Professeur, Ecole Polytechnique Fédérale de Lausanne, Examinateur

Michel DE LABACHELERIE, Directeur de Recherche, Institut FEMTO-ST, Examinateur

Sarah BENCHABANE, Chargé de Recherche, Institut FEMTO-ST, Co-directeur de thèse

Abdellatif AKJOUJ, Professeur, Université de Lille, Examinateur

Localization : Amphithéâtre Jean-Jacques Gagnepain (Institut FEMTO-ST, 15B Avenue des Montboucons, 25030 Besançon Cedex).