A laser diode apparatus has a first waveguide layer including a gain region connected in series with a second waveguide layer with a second gain region. A tunnel junction is positioned between the first and second guide layers. A single collimator is positioned in an output path of laser beams emitted from the first and second waveguide layers. The optical beam from the single collimator may be coupled into an optical fiber.

The upper surface of the semiconductor substrate has a slope descending from the projection in the second direction at an angle of 0-12° to a horizontal plane. The mesa stripe structure has an inclined surface with a slope ascending from the upper surface of the semiconductor substrate at an angle of 45-55° to the horizontal plane, the mesa stripe structure having an upright surface rising from the inclined surface at an angle of 85-95° to the horizontal plane. The buried layer is made from semiconductor with ruthenium doped therein and is in contact with the inclined surface and the upright surface. The inclined surface is as high as 80% or less of height from the upper surface of the semiconductor substrate to a lower surface of the quantum well layer and is as high as 0.3 μm or more.

In a semiconductor laser device, a semiconductor layer includes a first groove formed on both sides of a ridge, a pair of second recesses facing each other and between which the ridge is interposed on a side of a light emitting surface, and a pair of third grooves in parallel to the first groove from the light emitting surface and interposing the ridge therebetween.

A semiconductor laser element configured to emit laser light, the semiconductor laser element comprises a substrate; and a semiconductor layer provided on the substrate, wherein the semiconductor layer includes a waveguide extending in a predetermined direction and configured to emit the laser light from one end face of the waveguide, the substrate includes a plurality of cavity sections intersecting the predetermined direction and extending, the plurality of cavity sections are provided in the substrate such that at least parts of at least two cavity sections of the plurality of cavity sections overlap with each other along the predetermined direction, and a length of each of the plurality of cavity sections in a direction perpendicular to the predetermined direction is shorter than a length of the semiconductor laser element in the perpendicular direction.

A laser diode apparatus has a first waveguide layer including a gain region connected in series with a second waveguide layer with a second gain region. A tunnel junction is positioned between the first and second guide layers. A single collimator is positioned in an output path of laser beams emitted from the first and second waveguide layers. The optical beam from the single collimator may be coupled into an optical fiber.

A semiconductor optical device may include a semiconductor substrate; a mesa stripe structure that extends in a stripe shape in a first direction on the semiconductor substrate and includes a contact layer on a top layer; an adjacent layer on the semiconductor substrate and adjacent to the mesa stripe structure in a second direction orthogonal to the first direction; a passivation film that covers at least a part of the adjacent layer; a resin layer on the passivation film; an electrode that is electrically connected to the contact layer and extends continuously from the contact layer to the resin layer; and an inorganic insulating film that extends continuously from the resin layer to the passivation film under the electrode, is spaced apart from the mesa stripe structure, and is completely interposed between the electrode and the resin layer.

A quantum cascade laser includes a laser structure including a semiconductor stack and a semiconductor support, the laser structure having a first end face and a second end face opposite the first end face. The semiconductor stack is disposed on the semiconductor support. The laser structure includes a semiconductor mesa and a buried region, the semiconductor mesa including a core layer, and the buried region embedding the semiconductor mesa. The laser structure includes a first region, a second region, and a third region. The third region is provided between the first region and the second region. The first region includes the first end face. The semiconductor mesa includes a first stripe portion, a second stripe portion, and a first tapered portion, respectively, in the first region, the second region, and the third region. The first stripe portion and the second stripe portion have different mesa widths.

A surface-emitting laser array includes a plurality of surface-emitting laser elements, a plurality of optical elements, and a light shielding member. The plurality of surface-emitting laser elements are arranged on a first surface of a substrate and configured to emit light in a direction crossing the first surface. The plurality of optical elements are arranged on a second surface opposite to the first surface of the substrate to correspond to the surface-emitting laser elements and configured to change a radiation angle of the light. The light shielding member is arranged in a region between the optical elements on the second surface of the substrate.

A light-emitting device includes a vertical-cavity surface-emitting laser, the resonant cavity of which is transverse multimode supporting transverse modes having rotational symmetry of order two about a main optical axis, and an index-contrast grating including a plurality of pads. The pads include: a central pad, a plurality of peripheral pads, which are periodically arranged along one or more lines that are concentric with respect to the central pad, and which are arranged so that the grating has, with respect to the main optical axis, a rotational symmetry of uneven order higher than or equal to three.

In a semiconductor laser device, a semiconductor layer includes a first groove formed on both sides of a ridge, a pair of second recesses facing each other and between which the ridge is interposed on a side of a light emitting surface, and a pair of third grooves in parallel to the first groove from the light emitting surface and interposing the ridge therebetween.