Study On Topologically Nontrivial Photonic Materials And Propagation Properties Of Surface States

In recent decades,metamaterials have attracted tremendous amount of research attentions around the world.By taking advantage of their high tunability,scientists are expecting to fully taming the propagation properties of light.Till now,metamaterials have been exploited in their ability in realizing materials that are tough or even impossible to attain in nature,like negative index materials,hyperbolic materials,bianisotropic materials,chiral materials,etc.In recent years,they have been studied in applications like polarizers,zone plates,invisibility cloak,super resolution imaging,optical total absorption,holography,optical computing,etc.However,their properties as topological photonic devices are scarcely studied,due to the fact that they are normally strong dispersive materials.In a broader sense,topological properties of dispersive photonic materials are not understood by optical communities and physics communities yet.According to this condition,and that topological photonics is in the epicentre of recent years' photonic research,we investigate topological properties of strongly dispersive metamaterials as well as nature materials.The main content could be summarized as:First,we proposed the topological protected surface states on chiral-hyperbolic metamaterials.According to the intrinsic spin-orbital coupling of light,we report a method to calculate Chern numbers on equi-frequency surfaces of chiral-hyperbolic metamaterials.The topological protected surface states are found to resemble many similarities to the photonic floquet topological insulator.The topological protection is also confirmed in numerical simulations.Second,we design the first working chiral hyperbolic metamaterial within GHz frequency regime by apply both the slab approximation method and band structure method.The way we design the metamaterial may provide optimal guidelines for developing more complex metamaterials in the future.The topological properties are also justified in the designed real structure.Third,we developed Hamiltonian theory of chiral-hyperbolic metamaterial to try to fully understand its topological features from the fundamental physics point of view.The Hamiltonian was developed from the dispersion model of chiral metamaterial and gives rich topological features of this metamaterial.Our findings may pave way for developing topological photonic devices utilizing the dispersion degree of freedom.What's more,the Hamiltonian formalism may also be used in the finite difference time domain(FDTD)simulation method to better understand properties of chiral materials.Fourth,we report the first photonic Weyl points found in homogeneous material: magnetized plasma.By constructing the Hamiltonian of it,we have verified that the Weyl points are the only source/drain of Berry curvatures in this system.By angle-solved reflections experiment,locations of the Weyl points can be detected.What's more,the reflected light's polarization could reveal the complex half-plane-chirality in its polarization states which is identified as footprints of the Weyl points.These phenomenon could be fully understood from the effective Hamiltonian developed by k?p theory in magnetized plasma.We have also reported the topological surface states connecting Weyl point with different chirality,also the possible experimental scheme for verification.Apart from these,we also develop few spin-orbital interaction photonic devices,which can be summarized as:First,a biaxial hyperbolic metamaterial was designed based on Maxwell-Garnett effective medium theory.Its surface states are found always connecting Diabolic points of the metamaterial and could be effectively tuned by the covering medium's refractive index between concave,convex and even flat spatial dispersions.The surface states are found to be elliptically polarized and could introduce strong spin-orbital interaction of spinning incident light,which could be promising in application light integrated photonic devices and biosensing.Second,a bianisotropic metamaterial was found to support line degeneracy,and due to its polarization properties,it could cause strong spin-orbital coupling in the bulk metamaterial.The metamaterial was successfully designed within GHz regime,an analytical theory to retrieve its effective parameters based on simulated band structures is also developed.This finding could be applied in functional millimetre and centimetre devices.