title: Analysis of the modal evolution in fused-type mode-selective fiber couplers.
abstract: Fused-type mode-selective fiber couplers exciting the LP(11) mode are fabricated by well-defined fiber cladding reduction, pretapering and fusion. At a wavelength of 905 nm 80 % of the injected power in the single-mode fiber was transmitted in the few-mode fiber selectively exciting the LP(11) mode. The coupling behavior was experimentally investigated for the case of strong as well as weak fusion. Numerical simulations based on the super-mode coupling approach were used to estimate fabrication parameters and to discuss the modal evolution in arbitrarily fused couplers. The influence of changes in the coupler geometry on the super-modes and their modal weighting are analyzed by calculations of the effective refractive index and by modal decomposition.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Pelegrina-Bonilla
authors.forename: Katharina
authors.initials: K
authors.lastname: Hausmann
authors.forename: Hakan
authors.initials: H
authors.lastname: Sayinc
authors.forename: Uwe
authors.initials: U
authors.lastname: Morgner
authors.forename: Jörg
authors.initials: J
authors.lastname: Neumann
authors.forename: Dietmar
authors.initials: D
authors.lastname: Kracht