Pelegrina-Bonilla Gabriel, Hausmann Katharina, Sayinc Hakan, Morgner Uwe, Neumann Jörg, Kracht Dietmar
Opt Express. 2015 Sep 7;23(18):22977-90. doi: 10.1364/OE.23.022977.
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.
