The Absorption And Scattering Of Optical And Acoustical Meta-materials

In the optics and acoustics, absorption and scattering are of great interest. The conceptof coherent perfect absorber (CPA) has been proposed in optics. Its principle is to utilizethe interference effect of coherent light within the absorber, which is the inverse process oflaser light generation. Interestingly, such an absorber exhibits perfect (100%) absorption.However, the CPA can only achieve single-frequency absorption. And the requirement ofparameters for the CPA is so restrict that only some certain materials can be used to realizethe CPA. People proposed an artificial microstructure material-Metamaterials. Theeffective parameters of metamaterials can be tuned almost arbitrarily by manipulating themicro-structure. As a consequence, the metamaterials have become ideal materials for CPAdue to their unique properties. On the other hand, the sound absorption is also an importantand meaningful problem, which has very wide applications. In this thesis, we propose theCPA for acoustics based on acoustic metamaterials, and furtherly explore the possibility toachieve the broadband absorption.The dissertation is organized as follows:In the chapter one, we review the background and progress of the absorption andscattering. We also introduce the concept and applications of metamaterials.In the chapter two, we investigate the optical absorption and scattering, and give thebasc theory for the electromagnetic CPA.In the chapter three, we study the absorption and scattering of acoustic, and proposethe acoustic CPA. Analogous to the optical CPA, we derive the conditions of acoustic CPA.In the chapter four, we investigate conditions for the broadband acoustic absorption.Through utilizing appropriate Lorenz model, satisfying the required dispersion of the parameters to obtain broadband acoustic CPA is possible.