Biota, Inc.

Serge A Gurevich

Vera B Gorfinkel

The present invention relates to a separate confinement heterostructure laser, and in particular to a stripe geometry, ridge waveguide geometry, having an active layer positioned between a pair of n-type and p-type emitter layers which inject charge carriers under the ridge guide into the active layer. A pair of ohmic contacts are used to inject one type of charge carrier into at least one emitter layer outside the ridge area. When a signal is applied to the pumping contacts (p- and n-type) in forward bias and an intermittent electric field is applied to the ohmic side contacts, the flow of current injected by the side contacts controls the densities of carriers injected by the pumping contacts, thereby controlling spatially and temporally the optical gain and optical confinement factor. In another embodiment, a stripe geometry, ridge waveguide heterostructure laser is disclosed having pumping contacts under the ridge guide to an active layer between two emitter layers with a portion coextending transversely through the ridge and another portion extending laterally outside the ridge. A pair of electro-optic dielectric layers are positioned on the portion of one emitter layer extending outside the ridge. An electric field is applied to the emitter layers under the ridge contact to inject two types of charge carriers into the active layer, and an intermittent electric field is applied across the dielectric layer outside the ridge guide to modulate the refractive index, thereby controlling the optical mode shape. By synchronously applying signals to the pumping contacts and to the side contacts, modulation above 50 MHz can be attained and picosecond pulses can be generated in the devices of both embodiments, thereby reducing chirp and relaxation oscillations.

Method of and means for controlling the electromagnetic output power of

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.

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-carrier plasma in order to control light emission and absorption in the active layer. A heterojunction semiconductor laser is disclosed with two sets of electrical contacts: one to apply pumping currents and the other to control the electric field. Operating modes of the heterojunction devices are discussed which include high frequency (up to 100 GHz) modulation of the electromagnetic output of the laser, formation of picosecond optical pulses, and simultaneous amplitude modulation and mixing two signals by controlling synchronously the intensity, period and phase of pumping current and electric-field inside the active layer.

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Saint-Petersburg, Russia

Serge A Gurevich