An optical semiconductor integrated element comprises a laser section and a photodetector section which are arranged on the same semiconductor substrate, the laser section and the photodetector section each have a light confining layer which confines light, a cladding layer, and a contact layer formed of an InGaAs layer or an InGaAsP layer, the light confining layer of the laser section is an active layer, the contact layer of the photodetector section is a light absorption layer, each cladding layer is a ridge structure having a shape in which a width at a side of the light confining layer is narrower than a width at a side of the contact layer in a cross-section which is perpendicular to the optical axis, and on a side surface of the light confining layer, the cladding layer and the contact layer, a semiconductor embedded layer is not provided.

A semiconductor laser diode is specified, the semiconductor laser diode includes a semiconductor layer sequence having an active layer which has a main extension plane and which, in operation, is adapted to generate light in an active region and to emit light via a light-outcoupling surface, the active region extending from a rear surface opposite the light-outcoupling surface to the light-outcoupling surface along a longitudinal direction in the main extension plane, the semiconductor layer sequence having a surface region on which a first cladding layer is applied in direct contact, the first cladding layer having a transparent material from a material system different from the semiconductor layer sequence, and the first cladding layer being structured and having a first structure.

Techniques for efficient alignment of a semiconductor laser in a Photonic Integrated Circuit (PIC) are disclosed. In some embodiments, a photonic integrated circuit (PIC) may include a semiconductor laser that includes a laser mating surface, and a substrate that includes a substrate mating surface. A shape of the laser mating surface and a shape of the substrate mating surface may be configured to align the semiconductor laser with the substrate in three dimensions.

A Group III-Nitride quantum well laser including a distributed Bragg reflector (DBR). In some embodiments, the DBR includes Scandium. In some embodiments, the DBR includes Al.sub.1-xSc.sub.xN, which may have 0<x≤0.45.

Photonic devices having a photonic waveguiding layer, and a cladding layer, disposed on the photonic waveguiding layer, and where the cladding section is a material comprising Scandium. The cladding layer may include a material comprising Al.sub.1-xSc.sub.xN material where 0<x≤0.45.

An electrode comprising a Ti layer and a Pt layer that are sequentially laid on a surface of a p-type semiconductor layer. Further, a thermal impedance per unit area of a contact portion that is in contact with the surface of the p-type semiconductor layer is equal to or smaller than 1.2×10.sup.4 K/W.Math.m.sup.2.

Provided is a nitride semiconductor element that does not cause element breakdown even when driven at high current density. A nitride semiconductor element includes an active layer, an electron block layer formed above the active layer, an AlGaN layer formed on the electron block layer, and a cover layer covering an upper surface of the AlGaN layer and formed of AlGaN or GaN having a lower Al composition ratio than in the AlGaN layer, in which the AlGaN layer includes protrusions provided on a surface opposite to the active layer, and the cover layer covers the protrusions. The AlGaN layer is preferably formed of AlGaN having an Al composition ratio decreasing in a direction away from the active layer, and the protrusions preferably have a frustum shape.

An AlGaInPAs-based semiconductor laser device includes a substrate, an n-type clad layer, an n-type guide layer, an active layer, a p-type guide layer composed of AlGaInP containing Mg as a dopant, a p-type clad layer composed of AlInP containing Mg as a dopant, and a p-type cap layer composed of GaAs. Further, the semiconductor laser device has, between the p-type guide layer and the p-type clad layer, a Mg-atomic concentration peak which suppresses inflow of electrons, moving from the n-type clad layer to the active layer, into the p-type guide layer or the p-type clad layer.

A quantum cascade laser device includes a semiconductor substrate, an active layer provided on the semiconductor substrate, and an upper clad layer provided on a side of the active layer opposite to the semiconductor substrate side and having a doping concentration of impurities of less than 1×10.sup.17 cm.sup.−3. Unit laminates included in the active layer each include a first emission upper level, a second emission upper level, and at least one emission lower level in their subband level structure. The active layer is configured to generate light having a center wavelength of 10 μm or more due to electron transition between at least two levels of the first emission upper level, the second emission upper level, and the at least one emission lower level in the light emission layer in each of the unit laminates.

A semiconductor optical integrated device is a semiconductor optical integrated device in which a first optical element, a monitoring light waveguide and a second optical element, through which light propagates, are formed on a common semiconductor substrate; wherein the monitoring light waveguide is joined to the first optical element, and the second optical element is joined to the monitoring light waveguide. The monitoring light waveguide includes a light scattering portion for scattering a part of the light, which is composed of a combination of light waveguides having different mode field diameters or having different centers of mode field diameters; and a light detector for receiving scattered light scattered by the light scattering portion, is placed on an outer periphery of the monitoring light waveguide, or on a back surface of the semiconductor substrate on its side opposite to that facing the light scattering portion.