title: Cut-off analysis of 19-cell Yb-doped double-cladding rod-type photonic crystal fibers.
abstract: Yb-doped double-cladding large mode area rod-type photonic crystal fibers are a key component for power scaling in fiber laser systems. Recently, designs with 19-cell core defect, that is with 19 missing air-holes in the center of the photonic crystal cladding, have been proposed, with reported core diameter up to 100 μm. In this paper an analysis of the cut-off wavelength of the first high-order mode in such low-NA fibers is reported, accounting for different approaches for the definition of the cladding effective index. Results have shown that taking into account the finite fiber cross-section and considering the first cladding mode of the actual fiber is mandatory to obtain a correct estimate of the cut-off wavelength.
authors.affiliation: Information Engineering Department, University of Parma, I-43124 Parma, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Poli
authors.forename: E
authors.initials: E
authors.lastname: Coscelli
authors.forename: T T
authors.initials: TT
authors.lastname: Alkeskjold
authors.forename: D
authors.initials: D
authors.lastname: Passaro
authors.forename: A
authors.initials: A
authors.lastname: Cucinotta
authors.forename: L
authors.initials: L
authors.lastname: Leick
authors.forename: J
authors.initials: J
authors.lastname: Broeng
authors.forename: S
authors.initials: S
authors.lastname: Selleri