title: Axially symmetric fiber side pumping.
abstract: A method for axially symmetric fiber side pumping is proposed. The method is based on a coupling structure and a pump source that both utilize the axially symmetric geometry of a typical optical fiber. The coupling structure can be manufactured by adding material to and/or by removing material from the fiber. In principle, the method enables the launch of kilowatt-level pump power into the fiber through a single coupling structure. The conditions for successful coupling and a simple experimental verification of the method are presented. In the experiments over 90 % of the launched light fell inside the coupling area and the potential for efficient coupling into a double clad fiber was demonstrated.
authors.forename: Erkki
authors.initials: E
authors.lastname: Lassila
authors.forename: Rolf
authors.initials: R
authors.lastname: Hernberg
authors.forename: Taito
authors.initials: T
authors.lastname: Alahautala