The Study Of Induced Interface States In Classical Wave Systems In Analogy To Electronic Systems

The discovery of semiconductors gave people the capability to control the flow of electrons,which brought technological revolution and had a profound impact on human civilization.Analog to the periodic potentials in semiconductors,by stacking dielectric media/solid media periodically,photonic/acoustic crystals are possible to control the flow of electromagnetic/acoustic waves.In chapter 1,we introduce the concepts of photonic crystals(PCs)and acoustic crystals(ACs)and their development.The earlier work focused on the study of band-gapped structures.By introducing defects,hetero-structures and surface decorations,interface states and edge states can be created in PCs,which are crucial in terms of applications.Some recent works focus on the topological nature of classical waves.By analogy to topological insulators,topological photonic/acoustic structures were studied.In chapter 2,by making analogy to Su-Schrieffer–Heeger(SSH)model,deterministic interface states in two-dimensional(2D)ACs are realized.The bulk AC band properties are determined by its surface impedance which corresponds to the corresponding geometrical Zak phase.In both simulations and experiments,we verified the existence of the interface states between two ACs of different bulk band properties and the interface dispersion was measured.This type of deterministic interface states will ease the design procedure of acoustic waveguide and might be protected by topology.It may provide reference to the future design of novel acoustic devices.In chapter 3,we developed a novel numerical method of solving band diagrams of PC with dispersive media,based on the weak form equation in COMSOL.This method provides us a convenient simulation tool to study complex light analogy platform.We studied the band diagram of a PC with a dispersive negative background medium which is not easy for traditional numerical methods and interface states were obtained.The method itself will also largely decrease the simulation time needed to obtain the equi-frequency contours of PCs which will be helpful for some PC related application designs.In chapter 4,two acoustic measurement platforms based on the virtual instrument and Labview Software we developed are discussed.A 2D acoustic field mapping system is realized,using either oscilloscope with synchronous pulse signals or lock-in amplifier as receiving instruments.We also developed a device to obtain acoustic properties of metamaterials.Different to traditional impedance tube which has a large limitation on the size and shape of the sample,our device shall be more suitable for acoustic metamaterial designs.We developed experimental and numerical tools which will facilitate the analogical study to electronic systems using classical waves.The analogical classical platform will help the verification of condensed matter theories and we can also borrow some new ideas from condensed matter physics for the future design of photonic/acoustic devices.