Embodiments may relate to a multiple quantum well (MQW) laser for operating at high temperatures, comprising at least one quantum well made of compressively strained InGaAlAs layers that are alternatively stacked with tensile strained InGaAlAs layers, the at least one quantum well surrounded on one side by a n-doped InP cladding and on the other by a p-doped InP cladding so as to form a double hetero-junction. A confinement layer of lattice-matched InAlAs may be provided between the quantum well and the p-doped cladding, having a first surface facing or adjacent to the quantum well and a second surface facing or adjacent to the p-doped cladding. An additional electron containment layer of tensile strained InAlAs may be provided facing or adjacent to one surface of the confinement layer, having a thickness smaller than that of the confinement layer. Other embodiments may be described and/or claimed.

An edge-emitting semiconductor laser and a method for operating a semiconductor laser are disclosed. In an embodiment, the edge-emitting semiconductor laser includes an active zone within a semiconductor layer sequence and a stress layer. The active zone is configured for being energized only in a longitudinal strip perpendicular to a growth direction of the semiconductor layer sequence. The semiconductor layer sequence has a constant thickness throughout in the region of the longitudinal strip so that the semiconductor laser is gain-guided. The stress layer may locally stress the semiconductor layer sequence in a direction perpendicular to the longitudinal strip and in a direction perpendicular to the growth direction. A refractive index of the semiconductor layer sequence, in regions which, seen in plan view, are located next to the longitudinal strip, for the laser radiation generated during operation is reduced by at least 210.sup.4 and by at most 510.sup.3.

Embodiments may relate to a multiple quantum well (MQW) laser for operating at high temperatures, comprising at least one quantum well made of compressively strained InGaAlAs layers that are alternatively stacked with tensile strained InGaAlAs layers, the at least one quantum well surrounded on one side by a n-doped InP cladding and on the other by a p-doped InP cladding so as to form a double hetero-junction. A confinement layer of lattice-matched InAlAs may be provided between the quantum well and the p-doped cladding, having a first surface facing or adjacent to the quantum well and a second surface facing or adjacent to the p-doped cladding. An additional electron containment layer of tensile strained InAlAs may be provided facing or adjacent to one surface of the confinement layer, having a thickness smaller than that of the confinement layer. Other embodiments may be described and/or claimed.

An optical semiconductor device includes an InP substrate; an active layer disposed above the InP substrate; a n-type semiconductor layer disposed below the active layer; and a p-type clad layer disposed above the active layer, wherein the p-type clad layer includes one or more p-type In.sub.1-xAl.sub.xP layers, the Al composition x of each of the one or more p-type In.sub.1-xAl.sub.xP layers is equal to or greater than a value corresponding to the doping concentration of a p-type dopant, and the absolute value of the average strain amount of the whole of the p-type clad layer is equal to or less than the absolute value of a critical strain amount obtained by Matthews' relational expression, using the entire layer thickness of the whole of the p-type clad layer as a critical layer thickness.

A high-efficiency active layer includes a strained quantum well layer and, at one side thereof, a first strained barrier layer configured to transport electrons. The first strained barrier layer and the strained quantum well layers are configured to form strain compensation. A second barrier layer is positioned on the other side of the strained quantum well layer and is configured to transport holes. A band offset between conduction bands of the first strained barrier layer and of the strained quantum well layer is less than a band offset between valence bands of the strained quantum well layer and of the first strained barrier layer. A band offset between valence bands of the strained quantum well layer and of the second barrier layer is less than a band offset between conduction bands of the second barrier layer and of the strained quantum well layer. Light-emitting efficiency and reliability are improved.

A laser diode includes an active zone that emits radiation in a lateral emission angle range in a plane of the active zone via an emission side of a layer arrangement, an electrical contact is configured on a top side of the layer arrangement, the electrical contact includes a metallic adhesion layer and at least one metallic contact layer, the adhesion layer is arranged on the layer arrangement, the adhesion layer includes a layer stack including a first and a second layer, the first layer is arranged on the layer arrangement, the first layer is configured in a planar fashion, the second layer is subdivided into at least one first and at least one second partial surface, the adhesion layer is arranged in the first partial surface, and the contact layer is arranged on the first partial surface and in the second partial surface.

An array of monolithic wavelength division multiplexed (WDM) vertical cavity surface emitting lasers (VCSELs) is provided with quantum well intermixing. Each VCSEL includes a bottom distributed Bragg reflector (DBR), an upper distributed Bragg reflector, and a laser cavity therebetween. The laser cavity includes a multiple quantum well (MQW) layer sandwiched between a lower separate confinement heterostructure (SCH) and an upper SCH layer. Each MQW region experiences a different amount of quantum well intermixing and concomitantly a different lasing wavelength shift.

An array of monolithic wavelength division multiplexed (WDM) vertical cavity surface emitting lasers (VCSELs) is provided with quantum well intermixing. Each VCSEL includes a bottom distributed Bragg reflector (DBR), an upper distributed Bragg reflector, and a laser cavity therebetween. The laser cavity includes a multiple quantum well (MQW) layer sandwiched between a lower separate confinement heterostructure (SCH) and an upper SCH layer. Each MQW region experiences a different amount of quantum well intermixing and concomitantly a different lasing wavelength shift.

An interband cascade (IC) light emitting device comprising a plurality of interband cascade stages, wherein at least one of the IC stages is constructed to have an electron injector made of one or more QWs, a type-I quantum well (QW) active region, a barrier layer positioned between the active region and the electron injector, a hole injector made of one or more QWs, and a barrier layer positioned between the active region and the hole injector. In at least one embodiment, a type II heterointerface layer is between the electron injector and an adjacent hole injector. The well layer of the type-I QW active region has compressive strain, while the barrier layers which flank the type-I QW active region comprise tensile strain layers. In certain embodiments, the electron injector and the hole injector comprise tensile strained layers.

An improved longwave infrared quantum cascade laser. The improvement includes a strained In.sub.xGa.sub.1-xAs/Al.sub.yIn.sub.1-yAs composition, with x and y each between 0.53 and 1, an active region emitting at a wavelength equal to or greater than 8 m, an energy spacing E.sub.54 equal to or greater than 50 meV, an energy spacing E.sub.C4 equal to or greater than 250 meV, and an optical waveguide with a cladding layer on each side of the active region. Each cladding layer has a doping level of about 2.Math.10.sup.16 cm.sup.3. The optical waveguide also has a top InP layer with a doping level of about 5.Math.10.sup.16 cm.sup.3 and a bottom InP layer with a doping level of about 510.sup.16 cm.sup.3. Additionally, the optical waveguide has a plasmon layer with a doping level of about 8.Math.10.sup.18 cm.sup.3.