Title :
Analysis of the Coupling Mechanism in Asymmetric Fused Fiber Couplers
Author :
Pelegrina-Bonilla, Gabriel ; Hausmann, Kurt ; Tunnermann, Henrik ; Wesels, Peter ; Sayinc, Hakan ; Morgner, U. ; Neumann, Jorg ; Kracht, Dietmar
Author_Institution :
Laser Zentrum Hannover eV, Hannover, Germany
Abstract :
We investigated experimentally and numerically the coupling mechanism in asymmetric fused fiber couplers consisting of different single-mode fibers with unequal core diameter and numerical aperture. We increased the maximum coupled power by pretapering one of the fibers achieving a nearly complete power transfer at a specific pretaper length. Experimental results are compared to numerical results obtained by using our own 3-D FFT-based beam propagation method (BPM) algorithm. The numerical model explains qualitatively the coupler performance and allows to gain insight into the coupling mechanism. We discuss the influence of the fiber cores on the excited super-modes of the cladding structure. A modal decomposition of the light field is carried out in order to analyze the evolution of the super-modes and to discuss the influence of pretapering on the excitation of these modes.
Keywords :
Fourier transform optics; fast Fourier transforms; numerical analysis; optical fibre cladding; optical fibre couplers; 3D FFT-based beam propagation method algorithm; asymmetric fused fiber couplers; cladding structure; core diameter; coupled power; coupling mechanism; fiber pretapering; light field; modal decomposition; numerical aperture; numerical model; power transfer; pretaper length; single-mode fibers; Couplers; Couplings; Fabrication; Numerical models; Refractive index; Solid modeling; Three-dimensional displays; Asymmetric fused fiber couplers; beam propagation method (BPM); modal decomposition; single-mode fibers;
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2014.2325593
