title: Observation of valley-dependent beams in photonic graphene.
abstract: Valley-dependent propagation of light in an artificial photonic hexagonal lattice, akin to electrons in graphene, is investigated in microwave regime. Both numerical and experimental results show that the valley degeneracy in the photonic graphene is broken when the frequency is away from the Dirac point. The peculiar anisotropic wave transport property due to distinct valleys is analyzed using the equifrequency contours. More interestingly, the valley-dependent self-collimation and beam splitting phenomena are experimentally demonstrated with the armchair and zigzag interfaces, respectively. Our results confirm that there are two inequivalent Dirac points that lead to two distinct valleys in photonic graphene, which could be used to control the flow of light and might be used to carry information in valley polarized beam splitter, collimator or guiding device.
authors.forename: Fusheng
authors.initials: F
authors.lastname: Deng
authors.forename: Yong
authors.initials: Y
authors.lastname: Sun
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.forename: Rui
authors.initials: R
authors.lastname: Xue
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.forename: Haitao
authors.initials: H
authors.lastname: Jiang
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Shi
authors.forename: Kai
authors.initials: K
authors.lastname: Chang
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
mesh_terms: D003198:Computer Simulation; D004583:Electrons; D006108:Graphite / Q000737:chemistry*; D008027:Light; D017785:Photons; D012542:Scattering, Radiation
chemical_list: D006108:Graphite