title: All-fiber LP11 mode convertors.
abstract: We describe two all-fiber devices for converting light from the fundamental mode to the second-order set of modes in optical fibers. The first is made by controlled hole collapse in a photonic crystal fiber, and the second is a twisted fused coupler made from few-moded conventional fiber. As well as having applications within fiber optics, the devices can be used to generate azimuthally polarized free-space beams.
authors.affiliation: Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Witkowska
authors.forename: S G
authors.initials: SG
authors.lastname: Leon-Saval
authors.forename: A
authors.initials: A
authors.lastname: Pham
authors.forename: T A
authors.initials: TA
authors.lastname: Birks