A laser is provided, including: a distributed Bragg mirror; a waveguide, the laser to emit light radiation along a longitudinal direction x, and the waveguide formed at least in part in a stack of layers made of III-V materials including at least one active region to emit the light radiation, the mirror including lateral corrugations distributed periodically along the direction x in a period Λ, the corrugations being carried by at least a lateral plane xz defined by the direction x and a first transverse direction z normal to the direction x, the corrugations having a dimension d along a second transverse direction y normal to the direction x; and a top electrode arranged on the waveguide along the direction z, the corrugations being partly located at lateral flanks of the top electrode, extending parallel to the plane xz, and extending only on the lateral flanks of the top electrode.

A gain medium for semiconductor optical amplifier in high-power operation includes a substrate with n-type doping; a lower clad layer formed overlying the substrate; a lower optical confinement stack overlying the lower clad layer; an active layer comprising a multi-quantum-well heterostructure with multiple well layers characterized by about 0.8% to 1.2% compressive strain respectively separated by multiple barrier layers characterized by about −0.1% to −0.5% tensile strain. The active layer overlays the lower optical confinement stack. The gain medium further includes an upper optical confinement stack overlying the active layer, the upper optical confinement stack being set thinner than the lower optical confinement stack; an upper clad layer overlying the upper optical confinement stack; and a p-type contact layer overlying the upper clad layer.

A semiconductor device comprising a waveguide having a core, said core having inserted therein one or more layers of nanoemitters.

A manufacturing method of a nitride-based semiconductor light-emitting element includes: forming an n-type nitride-based semiconductor layer; forming, on the n-type nitride-based semiconductor layer, a light emission layer including a nitride-based semiconductor; forming, on the light emission layer in an atmosphere containing a hydrogen gas, a p-type nitride-based semiconductor layer while doping the p-type nitride-based semiconductor layer with a p-type dopant at a concentration of at least 2.0×10.sup.18 atom/cm.sup.3; and annealing the p-type nitride-based semiconductor layer at a temperature of at least 800 degrees Celsius in an atmosphere not containing hydrogen. In this manufacturing method, a hydrogen concentration of the p-type nitride-based semiconductor layer after the annealing is at most 5.0×10.sup.18 atom/cm.sup.3 and at most 5% of the concentration of the p-type dopant, and a hydrogen concentration of the light emission layer is at most 2.0×10.sup.17 atom/cm.sup.3.

A laser including a grating configured to reduce lasing threshold for a selected vertically confined mode as compared to other vertically confined modes.

A electro-absorption optical modulator includes a multiple quantum well composed of a plurality of layers including a plurality of quantum well layers and a plurality of barrier layers that are alternately stacked, the plurality of quantum well layers and the plurality of barrier layers including an acceptor and a donor; a p-type semiconductor layer in contact with an uppermost layer of the plurality of layers; and an n-type semiconductor layer in contact with a lowermost layer of the plurality of layers, the multiple quantum well being 10% or more and 150% or less of the p-type semiconductor layer in a p-type carrier concentration, and in the multiple quantum well, an effective carrier concentration which corresponds to a difference between the p-type carrier concentration and an n-type carrier concentration is ±10% or less of the p-type carrier concentration of the multiple quantum well.

An optical apparatus comprises a semiconductor substrate and an optical waveguide emitter. The optical waveguide emitter comprises an input waveguide section extending from a facet of the semiconductor substrate, a turning waveguide section optically coupled with the input waveguide section, and an output waveguide section extending to the same facet and optically coupled with the turning waveguide section. One or more of the input waveguide section, the turning waveguide section, and the output waveguide section comprises an optically active region.

A semiconductor laser array includes: a plurality of semiconductor lasers configured to oscillate in a single mode at oscillation wavelengths different from one another, each semiconductor laser including an active layer including a multi-quantum well structure including a plurality of will layers and a plurality of barrier layers laminated alternately, and an n-side separate confinement heterostructure layer and p-side separate confinement heterostructure layer configured to sandwich the active layer therebetween in a thickness direction, band gap energies of the n-side separate confinement heterostructure layer and the p-side separate confinement heterostructure layer being greater than band gap energies of the barrier layers of the active layer. The active layer is doped with an n-type impurity.

A semiconductor laser device includes: a main body including a first layer having n-type conductivity, a second layer having p-type conductivity, and an active layer interposed between the first layer and the second layer, the first layer, the second layer, and the active layer being laminated in a lamination direction; a front-side mirror formed on a front facet of the main body, the front facet being parallel to the lamination direction; and a rear-side mirror formed on a rear facet of the main body, the rear facet facing the front facet in an optical waveguide direction that crosses the lamination direction and the front facet. The first layer includes an electric field control layer having a shorter composition wavelength than an emission wavelength of the active layer. The second layer includes an optical guide layer having a shorter composition wavelength than the emission wavelength of the active layer.

A quantum cascade laser element includes: a semiconductor substrate; a semiconductor laminate including an active layer and having a first end surface and a second end surface facing each other in an optical waveguide direction; a first electrode; a second electrode; and an anti-reflection film formed on the first end surface. The semiconductor laminate is configured to oscillate laser light having a central wavelength of 7.5 μm or more. The anti-reflection film includes at least one of at least one layer of a CeO.sub.2 film formed by continuous sputtering and vacuum evaporation and a plurality of layers of CeO.sub.2 films formed by discrete sputtering and vacuum evaporation.