The output electromagnetic power of optoelectric heterojunction semiconductor devices having an active semiconductor layer with a mobile charge carrier plasma is controlled by applying a microwave electric field inside the active layer by means of at least two semiconductor contacts to the active layer that are conducting to at least one type of mobile charge carrier and blocking to another type of charge carrier. An electrical signal is applied inside the active layer to transform the distribution of energies and equivalent temperature of the charge carriers of the mobile charge carriers in order to control light emission and absorption in the active layer. A modulator is disclosed with two such semiconductor contacts on the active layer in which charge carriers are optically generated. A monolithically integrated, cavity-coupled laser and modulator is disclosed in which the laser and modulator are fabricated on a common substrate and the laser is a distributed feedback laser (DFB). Another monolithically integrated cavity-coupled laser and modulator is fabricated in which the laser and modulator are coupled Fabrey-Perot optical cavities separated by a low-loss, 1-3 um groove. Operating modes of the modulator and laser are disclosed which include synchronously controlling the intensity period and phase of the signal controlling the electric field inside the active layer of the modulator and the signal controlling the laser. Best mode of operation is disclosed in which the signal sources to the laser and modulator are synchronously controlled to a cavity-coupled monolithically integrated laser and modulator, thereby generating short pulses of photonic radiation at a high data rate and with best mode and spectral quality.