The invention concerns semiconductor optoelectronic components with ribbon-shaped waveguide supported by a substrate. According to the invention the ribbon includes lateral sides and a light output face, characterized by said ribbon including a portion curved by more than two degrees in relation to the normal to the light output face, and the lateral sides being inwardly sloped on the substrate. The optoelectronic component may be an electro-optical modulator, a semiconductor optical amplifier, a semiconductor laser or a Mach-Zehnder-type interferometer. The component may also be formed by joining two of these devices.