Yuxin LIU
Thesis defence
12/07/2019
IEMN Amphitheatre
Summary:
The control of elastic wave propagation relies mainly on the design of artificial media based on structured materials to achieve advanced engineering of propagation dispersion. During the thesis, the dispersion of the guided horizontal transverse polarisation mode (Love mode) in the SiO2/Quartz multilayer structure (ST-90° cut) was numerically investigated and the resulting applications explored. The properties of phononic crystals based on holes micromachined in the SiO2 layer were studied, as were the interaction mechanisms of this mode with studs deposited on the surface of this guiding layer. In the case of hole-based phononic crystals, we have shown that it is possible to open band gaps, and this property has been exploited in the design of a cavity resonator. The performance of the modes of this resonator is studied as a function of the geometrical parameters characterising the phononic crystal. It is also proposed to study the interaction of the cavity resonator modes with the resonance modes of studs deposited on the surface of the cavity. The geometric parameters of the studs are chosen so that the resonance modes of the studs and the cavity coincide. This results in better confinement of the modes and therefore a drastic improvement in the quality factor of the different modes. We also looked at the interaction between the Love mode and meta-surfaces based on studs deposited on the SiO2 surface. Couplings between pads of identical or different geometries gave rise to various phenomena such as the acoustic analogue of Autler-Townes Splitting (ATS), Fabry-Perot resonance, cavity modes, acoustically induced transparency (AIT) and Fano resonance. The results presented in this study could be used for potential acoustic applications such as signal processing, wave control, metamaterials and biosensors.
Abstract:
The control of the propagation of elastic waves relies mainly on the design of artificial medium based on structured materials to obtain an advanced engineering of the dispersion of the propagation. During the thesis, the dispersion of the shear horizontal polarised guided mode (Love mode) in the multilayer SiO2 / Quartz structure (90ST-cut) was numerically investigated and the resulting applications were explored. The properties of phononic crystals based on micro-machined holes in the SiO2 layer, as well as the interaction mechanisms of this mode with pillars deposited on the surface of this guiding layer, have been studied. In the case of hole-based phononic crystals we have shown that it is possible to open band gaps, this property has been exploited for the design of a cavity resonator. The performances of the modes of this resonator are studied according to the geometrical parameters characterizing the phononic crystal. It is also proposed to study the interaction of the modes of the cavity resonator with the resonance modes of pillars deposited on the surface of the cavity. The geometric parameters of the pillars are chosen so as to match the resonance modes of the pillars and the cavity. This has the effect of a better confinement of the modes and thus a drastic improvement of the quality factor of the different modes. We also investigated the interaction between the Love mode and meta-surfaces based on pillars deposited on the surface of SiO2. The couplings between pillars of identical or different geometries gave rise to various phenomena like acoustic analogue of Autler-Townes Splitting (ATS), Fabry-Perot resonance, cavity modes, acoustically induced transparency (AIT) and Fano resonance. The results presented in this study could be used for potential acoustic applications such as signal processing, wave control, meta-materials and biosensors.
JURY :
- Abdelkrim TALBI, Centrale Lille, Thesis supervisor
- Philippe PERNOD, Centrale Lille, Thesis Co-Director
- Olivier BOU MATAR, Centrale Lille, Thesis Co-Director
- Corinne DEJOUS, University of Bordeaux I, Rapporteur
- Bernard BONELLO, CNRS, Rapporteur
- El Houssaine EL BOUDOUTI, Mohammed I University, Examiner
- Virginie BLONDEAU-PATISSIER, University of Franche-Comté, Examiner
- Bahram DJAFARI-ROUHANI, University of Lille, Examiner
