Siemens Aktiengesellschaft

Wolfgang Thulke

Markus-Christian Amann

Stefan Illek

Gerhard Baumann

Gerhard Winzer

Hans F Mahlein

Jochen Heinen

Thomas Wolf

Bernhard Stegmueller

Ulrich Wolff

A modulatable laser diode for high frequencies, such as a tuneable turn guide distributed feedback laser diode, that has a central layer provided for a separate current supply located between a tuning layer and an active layer. The tuning layer has a quantum well structure. A ridge waveguide is provided for the laser diode and the layer sequence is limited to a strip-shaped mesa on the substrate in order to reduce the parasitic capacitances.

Modulatable laser diode for high frequencies

A tunable laser diode on a semi-insulating substrate having a stripe-shaped layer structure has an intermediate layer between an active layer and a tuning layer that is grown-over by an confinement layer that is doped for the same conductivity type as the intermediate layer. An oppositely doped, lateral region is electrically connected via an identically doped lower region to the active layer. An upper region is likewise oppositely doped and is electrically connected to the tuning layer. A contact layer is essentially planarly applied on the surface of the confinement layer and has respective portions on the appertaining regions on which the contacts provided with adequate bond areas are applied with a further contact layer for the common contact.

Tunable semiconductor laser on a semi-insulating substrate

A TTG-DFB laser diode on a doped substrate having a stripe-shaped layer structure that has an intermediate layer between an active layer and a tuning layer. A confinement layer laterally adjoins this layer structure at both sides, is doped for the same conductivity type as the substrate and is electrically conductively connected to the substrate through an interruption of the layers situated therebelow. An upper region, that respectively extends up to the surface and that is oppositely doped, is formed in the confinement layer above the layer structure. A lateral region, separated therefrom and that is electrically conductively connected via a lower confinement layer to a side of the layer structure facing toward the substrate, is formed in the confinement layer. Contact layers and contacts are applied on the upper region and on the lateral region, and a contact is applied on the substrate, so that separate current injection into both the active layer and the tuning layer is possible through the intermediate layer.

TTG-DFB laser diode

A monolithically integrated laser diode waveguide combination on a semi-insulating substrate has in an active region thereof a laser diode with a waveguide layer, an intermediate layer, an active layer, and a grating layer arranged between portions of a lower cover layer. Above this laser strip, an upper cover layer with a central contact layer is located thereupon together with a central contact. An activation of the active layer occurs via the lower cover layer, a lateral contact layer applied on the coating layer, and lateral contacts.

Monolithically integrated laser-diode-waveguide combination

Laser diode with buried active layer and lateral current limitation

A tunable semiconductor laser which is formed on a substrate 2 which has a first contact 14 on one surface and a third contact 16 on the opposite surface so as to supply the operating current which is laterally limited to a laser-active stripe through a barrier layer 4 l and including a second contact 15 on a ridge waveguide 11, 12, 13 so as to inject charge carriers into a tuning layer 9 mounted adjacent an active layer 6 and which is separated from the active layer by highly doped central layer 10 so as to allow tuning of the laser.

Tunable semiconductor laser

In the manufacture of laser diodes having a stripe-shaped, active layer, a problem arises upon application of lateral layers, particularly of blocking pn-junctions for lateral current conduction, in that these layers are undesired above the active layer. By applying a protective cover layer that will dissolve in super-cooled melts of the material of the lateral layers, before the growth of the lateral layers, the growth of the lateral layers, particularly blocking pn-junctions, above the active stripe is avoided since the cover layer dissolves in the melt given epitaxial application of the lateral layers.

Method and manufacturing a laser diode with buried active layer

A method for integrating a DFB laser and a passive strip waveguide on a substrate. A layer stack is produced in a first epitaxy step, the layer stack having a laser-active layer and a surface-wide grating on the uppermost layer, and eroding the stack area-wise, but only down to a layer under the laser-active layer, not down to the substrate, by means of etching to create a step separating the laser region from the passive strip waveguide region. By employing an etching stop layer, the etching can ensue self-adjustingly, and the coupling between the laser-active layer and the passive strip waveguide region occurs not by end coupling, but by surface coupling. Only two epitaxy steps are required for the complete manufacture of the structure, and a strip required for the definition of the laser and of the waveguide can be produced in the same single method step.

Growing community of inventors

Munich, Germany

Wolfgang Thulke