A monolithically integrated opto-electronic semiconductor component characterized by a semiconductor substrate having a first surface and a second surface extending parallel to each other, a strip waveguide being applied to the first surface to conduct radiation, such as light, in a path parallel to the first surface, a coupling element for coupling radiation from the strip waveguide through the substrate to a region on the second surface, a photodetector being applied to the second surface at the region for receiving the light which has been coupled laterally from the strip waveguide through the substrate. Preferably, the coupling means comprises a V-shaped groove having slanting surfavces forming a mirror which reflects the light substantially at right angles to the path in the strip waveguide.