Convergence Tests for the Piecewise Parabolic Method and Navier - Stokes Solutions for Homoge - neou

A multichannel coupler for connecting a plurality of input fibers to a plurality of output fibers which comprises a mixing fiber coupled to the pluralities of fibers. This mixing fiber is cut along a transversal cut and the two parts thus obtained are secured end to end. At least one of the surfaces delimiting the cut is ground for having a better distribution of the transmitted light onto the output fibers.