A semiconductor laser including an active zone and a waveguide, wherein the active zone includes an active layer configured to generate electromagnetic radiation during operation of the semiconductor laser, the waveguide is configured to guide the electromagnetic radiation generated during operation of the semiconductor laser within the semiconductor laser, the waveguide includes a subregion formed from a compound semiconductor material, wherein a proportion of a material of the compound semiconductor material gradually increases in the entire subregion along the vertical direction toward the active zone so that a refractive index of the subregion gradually decreases toward the active zone, and the proportion is an aluminum proportion or a phosphorus proportion.

In an embodiment, the gain-guided semiconductor laser includes a semiconductor layer sequence and electrical contact pads. The semiconductor layer sequence includes an active zone for radiation generation, a waveguide layer, and a cladding layer. The semiconductor layer sequence further includes a current diaphragm layer which is electrically conductive along a resonator axis (R) in a central region and electrically insulating in adjoining edge regions. Transverse to the resonator axis (R), the central region includes a width of at least 10 ?m and the edge regions includes at least a minimum width. The minimum width is 3 ?m or more. Seen in plan view, the semiconductor layer sequence as well as at least one of the contact pads on the semiconductor layer sequence are continuous components extending in the central region as well as on both sides at least up to the minimum width in the direction transverse to the resonator axis (R) adjoining the central region and beyond the central region.

Semiconductor Quantum Cascade Lasers (QCLs), in particular mid-IR lasers emitting at wavelengths of about 3-50 m, are often designed as deep etched buried heterostructure QCLs. The buried heterostructure configuration is favored since the high thermal conductivity of the burying layers, usually of InP, and the low losses guarantee devices high power and high performance. However, if such QCLs are designed for and operated at short wavelengths, a severe disadvantage shows up: the high electric field necessary for such operation drives the operating current partly inside the insulating burying layer. This reduces the current injected into the active region and produces thermal losses, thus degrading performance of the QCL. The invention solves this problem by providing, within the burying layers, effectively designed current blocking or quantum barriers of, e.g. AIAs, InAIAs, InGaAs, InGaAsP, or InGaSb, sandwiched between the usual InP or other burying layers, intrinsic or Fe-doped. These quantum barriers reduce the described negative effect greatly and controllably, resulting in a QCL operating effectively also at short wavelengths and/or in high electric fields.

A device may include a substrate and an active region. This active region may include a stack of semiconductor gain materials stacked along a stacking direction. The latter may extend substantially perpendicular to a plane of the substrate. The active region may be furthermore tapered so as to widen toward the substrate. In addition, the device may include a pair of doped layers semiconductor materials, the pair may include an n-doped layer and a p-doped layer arranged on the substrate and on opposite. The doped layers may be arranged on the substrate and on opposite, lateral sides of the tapered active region, respectively. The device may include an electron blocking layer, which may extend both at a first interface, between a p-doped layer and the substrate, and at a second interface, between the tapered active region and the p-doped layer, along a lateral side of the tapered active region.

A semiconductor laser includes a semiconductor layer sequence having an n-conducting n-region, a p-conducting p-region and an intermediate active zone, an electrically conductive p-contact layer that impresses current directly into the p-region and is made of a transparent conductive oxide, and an electrically conductive and metallic p-contact structure located directly on the p-contact layer, wherein the semiconductor layer sequence includes two facets forming resonator end faces for the laser radiation, in at least one current-protection region directly on at least one of the facets a current impression into the p-region is suppressed, the p-contact structure terminates flush with the associated facet so that the p-contact structure does not protrude beyond the associated facet and vice versa, and the p-contact layer is removed from at least one of the current-protection regions and in this current-protection region the p-contact structure is in direct contact with the p-region over the whole area.

A device may include a substrate and an active region. This active region may include a stack of semiconductor gain materials stacked along a stacking direction. The latter may extend substantially perpendicular to a plane of the substrate. The active region may be furthermore tapered so as to widen toward the substrate. In addition, the device may include a pair of doped layers semiconductor materials, the pair may include an n-doped layer and a p-doped layer arranged on the substrate and on opposite. The doped layers may be arranged on the substrate and on opposite, lateral sides of the tapered active region, respectively. The device may include an electron blocking layer, which may extend both at a first interface, between a p-doped layer and the substrate, and at a second interface, between the tapered active region and the p-doped layer, along a lateral side of the tapered active region.

In a nitride semiconductor laser element, a first epilayer including an active layer, a current confinement layer having an opening portion, and a second epilayer are formed on a semiconductor substrate. The first epilayer has an impurity concentration maximum portion where a concentration distribution of an impurity in a depth direction shows a local maximum near an interface with the current confinement layer.

A light-emitting element includes a mesa structure in which a first compound semiconductor layer of a first conductivity type, an active layer, and a second compound semiconductor layer of a second conductivity type are disposed in that order, wherein at least one of the first compound semiconductor layer and the second compound semiconductor layer has a current constriction region surrounded by an insulation region extending inward from a sidewall portion of the mesa structure; a wall structure disposed so as to surround the mesa structure; at least one bridge structure connecting the mesa structure and the wall structure, the wall structure and the bridge structure each having the same layer structure as the portion of the mesa structure in which the insulation region is provided; a first electrode; and a second electrode disposed on a top face of the wall structure.

A method for making a laser diode with a distributed grating reflector (RT) in a planar section of a semiconductor laser with stabilized wavelength includes providing a diode formed by a substrate (S), a first cladding layer (CL1) arranged on the substrate (S), an active layer (A) arranged on the first cladding layer (CL1) and adapted to emit a radiation, and a second cladding layer (CL2) arranged on the active layer (A), said cladding layers (CL1, CL2) being adapted to form a heterojunction to allow for efficient injection of current into the active layer (A) and optical confinement, and a contact layer. The manufacturing method provides for creating, on a first portion (ZA) of the device, a waveguide (GO) for confinement of the optical radiation and, on the remaining portion (ZP) of the device, two different gratings for light reflection and confinement. The two gratings define two different zones (R1, R2), wherein the first zone (R1) includes a grating of low order and high duty cycle, and is intended for reflection, and the second zone (R2) includes a grating of the same order, or a grating of a higher order than the previous one, and low duty cycle, and is mainly intended for light confinement. The waveguide (GO) for confining the optical radiation is implemented through a lithography and a subsequent etching, whereas the grating (RT) requires a high-resolution lithography and a shallow etching starting from a planar zone.

A semiconductor laser includes a semiconductor layer sequence having an n-conducting n-region, a p-conducting p-region and an intermediate active zone, an electrically conductive p-contact layer that impresses current directly into the p-region and is made of a transparent conductive oxide, and an electrically conductive and metallic p-contact structure located directly on the p-contact layer, wherein the semiconductor layer sequence includes two facets forming resonator end faces for the laser radiation, in at least one current-protection region directly on at least one of the facets a current impression into the p-region is suppressed, the p-contact structure terminates flush with the associated facet so that the p-contact structure does not protrude beyond the associated facet and vice versa, and the p-contact layer is removed from at least one of the current-protection regions and in this current-protection region the p-contact structure is in direct contact with the p-region over the whole area.