Complex band structures of 1D anisotropic graphene photonic crystal

The complex band structures of a 1D anisotropic graphene photonic crystal are investigated, and the dispersion relations are confirmed using the transfer matrix method and simulation of commercial software. It is found that the result of using effective medium theory can fit the derived dispersion curves in the low wave vector.Transmission, absorption, and reflection at oblique incident angles are studied for the structure, respectively.Omni-gaps exist for angles as high as 80° for two polarizations. Physical mechanisms of the tunable dispersion and transmission are explained by the permittivity of graphene and the effective permittivity of the multilayerstructure.

Size effect on light propagation modulation near band edges in one-dimensional periodic structures

Periodic photonic structures can provide rich modulation in propagation of light due to well-defined band structures.Especially near band edges,light localization and the effect of near-zero refractive index have attracted wide attention.However,the practically fabricated structures can only have finite size,i.e.,limited numbers of periods,leading to changes of the light propagation modulation compared with infinite structures.Here,we study the size effect on light localization and near-zero refractive-index propagation near band edges in one-dimensional periodic structures.Near edges of the band gap,as the structure's size shrinks,the broadening of the band gap and the weakening of the light localization are discovered.When the size is small,an added layer on the surface will perform large modulation in the group velocity.Near the degenerate point with Dirac-like dispersion,the zero-refractive-index effects like the zero-phase difference and near-unity transmittance retain as the size changes,while absolute group velocity fluctuates when the size shrinks.

Bending Loss Analysis of Optical Fiber with Out-Cladding of Photonic Crystals

A new type of optical fiber is presented here. It consists of a coaxial optical fiber, bounded by dielectric, multilayer and omnidirectional reflecting mirrors. Jones matrix method is used to analyze the influence of the layer number of one Dimensional (1D) photonic crystals on their reflectivity. The numerical results show that this type of fiber can be used to guide light around sharp bends whose radius of curvature can be as small as the wavelength of light without significant scattering losses.

Enhanced spectral splitting in a novel solar spectrum optical splitter based on one dimensional photonic crystal heterostructure

Controlling the distribution of solar spectrum in different bands would boost the energy harvesting efficiency and optimize the energy dispatchability.1D photonic crystal with intrinsic optical band gap can be used to split the solar spectrum for hybrid photovoltaic/thermal solar applications.Here,we designed an efficient solar spectrum optical filter based on a cermet layer,Si/SiO_(2)1D photonic crystal,and top heterostructure layer.Compared with 1D photonic crystal structure,the 1D photonic crystal heterostructure with top YSZ layer can realize the reflectance of greater than 92%in PV band and the low average reflectance in two thermal bands by tuning the effective impedance of multilayer films.The enhanced reflectance in PV band results from the huge mismatching of impedance between free space and the heterostructure structure.The top dielectric layer can also be extended to other oxides.