Monolithically integrated semiconductor laser-modulator combination

A monolithically integrated combination of a laser diode and a modulator is disclosed. An area of a common active stratified structure (2) is used for the laser and an adjacent part of said stratified structure is used for the modulator. The stratified structure is an MQW structure with mutually decoupled asymmetrical potential wells. The material compositions in the potential wells have the smallest energy bandgap at the n-side and are adapted in such a way to the stratified structure that when a potential difference is applied in the blocking direction, there occurs a blue shift of the absorption edge beyond the laser wavelength.