Abstract: A coupling device between a glass fiber and a dielectric waveguide integrated on a substrate. A low-loss and low-back-scatter, but cost-effective coupling is achieved by that the fiber end being reduced--principally by drawing under heat exposure until breaking--to a diameter in the order of typical core dimensions of dielectric waveguides. A fiber receiving portion is provided on the substrate dimensions reduced in a way substantially corresponding to the glass fiber and the tip thereof changing over into the waveguide to be coupled. The glass fiber, during assembly, need only be inserted into the receiving portion up to a stop, where it is centered with respect to the waveguide, without tolerances.