title: Photonic crystal fiber design for broadband directional coupling.
abstract: A novel design for a broadband directional coupler based on a photonic crystal fiber is investigated numerically. It is shown that suitable index-depressing doping of the core regions in an index-guiding twin-core photonic crystal fiber can stabilize the coupling coefficient between the cores over an extremely broad (octave-spanning) frequency range.
authors.affiliation: Research Center COM, Technical University of Denmark, Building 345v, DK-2800 Kongens Lyngby, Denmark. jl@com.dtu.dk
authors.forename: Jesper
authors.initials: J
authors.lastname: Laegsgaard
authors.forename: Ole
authors.initials: O
authors.lastname: Bang
authors.forename: Anders
authors.initials: A
authors.lastname: Bjarklev