Design And Research On Graphene-based Topological Photonic Crystal

The study of topological states is a hot topic in condensed matter physics.It is a novel electronic state generated by integral topological property of system.Quantum Hall effect,quantum spin Hall effect and topological insulator all have topological states.Their characteristics are insulated in its interior and protected by topology at the surface.Recently,many theoretical and experimental studies have demonstrated photonic analogues of topological states,based on the fact that these states are a manifestation of one-particle wave behavior,and this has further stimulated research on photonic topological states.Photonic crystals and metamaterials provide a flexible platform for simulating topological phases.The introduction of topology makes traditional photonic system have some new features,including unidirectional transport edge states,robustness of immunizing defects and no backscattering.Topological photonic is hopeful to provide huge revolution for photonic integration chip and optic communication devices.However,the application of topological photonic device is still facing much challenge.It is difficult to achieve topological photonic device at optical frequency.Devices are complex and big,so it is difficult to fabricate and integration.In this paper,we propose a graphene-based dielectric topological photonic crystal slab.Nontrival topological photonic cystal can be construct by lattice perturbation and deformation.We can achieve topological edge state waveguide transport.Our proposed structure has smaller dimension and is convenient for integration.Furthermore,the achievement of topological photonic states at optical frequencies is much easier in this designed structure.At the same time,it has simple design and is easier to fabricate.Most of all,topological edge state in the structure is continuously and dynamically tunable.The main works are as follows:1.Introduce the concept of photonic crystals and topological physics briefly.Discuss geometry phase in detail.It is helpful to understand essential of topological physics.Lastly,summarize the current research situation of topological photonics.2.Discuss calculation method of photonic crystals and deduce Plane-wave Expansion Method.Explain related theory and calculation method of topological photonics.Analyze optical properties of graphene and explain possibility of tuning photonic band by varying bias votage.3.We propose a graphene-based dielectric topological photonic crystal slab structure.And research the properties of photonic band,photonic pseudo-spin states and topological edge states.At last,check the robustness of topological edge states.4.We design a tunable topological photonic crystal structure,and research how varying chemical potential of graphene influence photonic band.We achieve tunability of topological edge states at 60-120 THz by varying bias votage.