A semiconductor laser (2) includes an n-type semiconductor substrate (1), a stack of an n-type cladding layer (4), an active layer (5), and a p-type cladding layer (6) successively stacked on the n-type semiconductor substrate (1). An optical waveguide (3) includes a non-impurity-doped core layer (9) provided on a light output side of the semiconductor laser (2) on the n-type semiconductor substrate (1) and having a larger forbidden band width than the active layer (5), and a cladding layer (10) provided on the core layer (9) and having a lower carrier concentration than the p-type cladding layer (6). The semiconductor laser (2) includes a carrier injection region (X1), and a non-carrier-injection region (X2) provided between the carrier injection region (X1) and the optical waveguide (3).

A laser chip including a plurality of stripes is disclosed, where a laser stripe can be grown with an initial optical gain profile, and its optical gain profile can be shifted by using an intermixing process. In this manner, multiple laser stripes can be formed on the same laser chip from the same epitaxial wafer, where at least one laser stripe can have an optical gain profile shifted relative to another laser stripe. For example, each laser stripe can have a shifted optical gain profile relative to its neighboring laser stripe, thereby each laser stripe can emit light with a different range of wavelengths. The laser chip can emit light across a wide range of wavelengths. Examples of the disclosure further includes different regions of a given laser stripe having different intermixing amounts.

A semiconductor laser (2) includes an n-type semiconductor substrate (1), a stack of an n-type cladding layer (4), an active layer (5), and a p-type cladding layer (6) successively stacked on the n-type semiconductor substrate (1). An optical waveguide (3) includes a non-impurity-doped core layer (9) provided on a light output side of the semiconductor laser (2) on the n-type semiconductor substrate (1) and having a larger forbidden band width than the active layer (5), and a cladding layer (10) provided on the core layer (9) and having a lower carrier concentration than the p-type cladding layer (6). The semiconductor laser (2) includes a carrier injection region (X1), and a non-carrier-injection region (X2) provided between the carrier injection region (X1) and the optical waveguide (3).

A laser device with one or more active regions, such as quantum wells, gain/lighting media, or other devices, and one or more non-absorbing regions, may be formed by a first growth run (growing a first semiconductor layer), then performing selective, shallow-depth etching, and then a second growth run (growing a second semiconductor layer). The laser device may include a first portion, one or more active regions located on the first portion, and a second portion located on the active region(s). A third portion may be located on one or more ends of the first portion and on the second portion. The third portion may be formed during the second growth run, after the etching step. The non-absorbing region(s) may be formed by the third portion and the end(s) of the first portion. If desired, the non-absorbing region(s) may be produced without annealing or locally-induced quantum well intermixing.

A quantum cascade laser includes a laser structure including first and second end faces, the laser structure including a semiconductor laminate region and a first embedding semiconductor region. The laser structure includes first and second regions arranged in a direction of a first axis extending from the first to second end faces. Each of the first and second regions includes the semiconductor laminate region. The semiconductor laminate region of the first region has a first recess. The semiconductor laminate region of the second region has a semiconductor mesa. The first recess and the semiconductor mesa extend in the direction of the first axis, and are aligned with each other. The semiconductor mesa has an end face extending in a direction of a second axis intersecting the first axis. The first embedding semiconductor region is disposed in the first recess so as to embed the end face of the semiconductor mesa.

In an embodiment a method for manufacturing a light-emitting semiconductor chip includes providing a substrate having a main surface with at least one recess, the main surface having a main extension plane along the longitudinal direction and along a transversal direction perpendicular to the longitudinal direction, wherein the substrate has pre-patterning trenches formed along the transversal direction between chip regions and extending along the longitudinal direction, growing the semiconductor layer sequence on the main surface with the at least one recess and forming at least one facet aligned along the transversal direction in the semiconductor layer sequence by an etching process, wherein the facet has a distance of less than or equal to 50 ?m from the at least one recess in at least one direction parallel to the main extension plane of the main surface.

A semiconductor laser apparatus is provided and has a substrate, a first type cladding layer, a first type waveguide layer, an active layer, a second type waveguide layer, a second type cladding layer, and a capping layer disposed in sequence. The active layer has a light producing portion and a light emitting portion. A laser produced by the light producing portion, emits along a direction from the light producing portion toward the light emitting portion. The light emitting portion includes a first inactive region, a light emitting region, and a second inactive region. A refractive index of the light emitting region is lower than a refractive index of the first inactive region, the refractive index of the light emitting region is lower than a refractive index of the second inactive region, and width of a first part of the light emitting region continuously increases along the direction.

A semiconductor laser apparatus is provided and has a substrate, a first type cladding layer, a first type waveguide layer, an active layer, a second type waveguide layer, a second type cladding layer, and a capping layer disposed in sequence. The active layer has a light producing portion and a light emitting portion. A laser produced by the light producing portion, emits along a direction from the light producing portion toward the light emitting portion. The light emitting portion includes a first inactive region, a light emitting region, and a second inactive region. A refractive index of the light emitting region is lower than a refractive index of the first inactive region, the refractive index of the light emitting region is lower than a refractive index of the second inactive region, and width of a first part of the light emitting region continuously increases along the direction.

A quantum cascade laser includes a laser structure including first and second end faces, the laser structure including a semiconductor laminate region and a first embedding semiconductor region. The laser structure includes first and second regions arranged in a direction of a first axis extending from the first to second end faces. Each of the first and second regions includes the semiconductor laminate region. The semiconductor laminate region of the first region has a first recess. The semiconductor laminate region of the second region has a semiconductor mesa. The first recess and the semiconductor mesa extend in the direction of the first axis, and are aligned with each other. The semiconductor mesa has an end face extending in a direction of a second axis intersecting the first axis. The first embedding semiconductor region is disposed in the first recess so as to embed the end face of the semiconductor mesa.

An optical semiconductor device has a semiconductor laser which emits front-end-surface-side emergent light on the front end surface side and emits rear-end-surface-side emergent light on the rear end surface side, and a mount substrate having the semiconductor laser provided on its front surface. The rear-end-surface-side emergent light is emitted while having an emergence optical axis that extends away from the mount substrate with increase in distance from the rear end surface.