title: Dual-negative refraction in photonic crystals with hexagonal lattices.
abstract: We present a dual-negative refraction effect based on the overlapping bands in a two-dimensional triangular photonic crystal formed by holographic lithography. Under certain conditions, one incident plane wave launched into this photonic crystal can be dispersed into two negative refracted waves at the same frequency and the same perpendicular polarization state with different phase velocities and group velocities. We find that this dual-negative refraction behavior can be easily manipulated by adjusting the incident angle, the frequency of incident wave and the filling ratio of the PhC. This special effect can be applied to realize wave-front division and optical interference in optical holography. Based on this effect, a double focusing imaging phenomenon has been achieved by the PhC slab. These unique features may show great impacts on both fundamental physics and optical device applications.
authors.affiliation: Department of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China. gydong@tsinghua.edu.cn
authors.forename: G Y
authors.initials: GY
authors.lastname: Dong
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: X L
authors.initials: XL
authors.lastname: Yang
authors.forename: L Z
authors.initials: LZ
authors.lastname: Cai
mesh_terms: D003460:Crystallization / Q000379:methods*; D004574:Electromagnetic Fields; D004867:Equipment Design; D006696:Holography / Q000379:methods*; D008420:Manufactured Materials; D036103:Nanotechnology / Q000379:methods*; D055095:Optics and Photonics / Q000379:methods*; D012031:Refractometry / Q000379:methods*