Sharp Kabushiki Kaisha Corporation

Martin David Dawson

Geoffrey Duggan

Timothy David Bestwick

Haruhisa Takiguchi

Alistair Henderson Kean

Kousei Takahashi

A single cavity mode optoelectronic device, such as a VCSEL, an RCLED or a DFB laser diode, comprises an etched-pillar or mesa structure including an optically active region and strain-applying means in the form of a layer of polymer material having a coefficient of thermal expansion which is greater than that of the optically active region. The layer surrounds the optically active region so as to apply a compressive strain to the latter so as to compensate at least partially for temperature-induced changes in the gain spectrum peak of the optically active region caused by ohmic heating of the device.

Optoelectronic devices

A surface-emitting laser contains an optical cavity including a multiple quantum well (MQW) active region providing a source of optical emission in use. Top and bottom mirrors are disposed respectively above and below the MQW active region. The MQW active region is profiled so that it has a greater number of quantum wells in a central portion thereof than in a peripheral portion thereof. In alternative embodiments, a current-guiding region is profiled so that it has a first current-guiding portion with a relatively smaller aperture therethrough extending over a central portion of the MQW active region, and a second current-guiding portion with a relatively larger aperture therethrough; and one of the mirrors has a layer structure which, in a central portion of the cross-sectional area of such mirror, is different to that in a peripheral portion of said cross-sectional area.

Surface-emitting laser

A quantum confined device is provided having raised portions formed on opposing walls of a groove, thereby defining a region of reduced width in the vicinity of the intersection of the walls. During fabrication, a 'V' groove is formed in a substrate and then further masking and etching steps are performed on the walls of the groove to form the raised portions. Quantum confined devices can be formed within the groove by epitaxial deposition of semiconducting layers into the region of reduced width.

Quantum device and method of making such a device

A quantum well structure is provided which is capable of efficiently confining electrons and holes in a quantum well layer. The quantum well structure includes a first cladding layer, a second cladding layer, and a plurality of quantum well layers and one or more barrier layers each disposed between the first cladding layer and the second cladding layer. The quantum well layers and the barrier layers are laminated in an alternating manner. The quantum well layers include at least two selected from the group consisting of a layer having tensile strain, a layer having no strain, and a layer having compressive strain. The thickness of each of the quantum well layers is selected so that the energy difference in each of the quantum well layers between the ground quantum state of an electron at the conduction band and the ground quantum state of a hole at the valence band is substantially the same.

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Oxford, United Kingdom

Martin David Dawson