A light-emitting device includes a light emission section (Em), a separation groove (152), and a high reflectance region (Hr). The light emission section (Em) includes a stack structure (100) including an active layer (100), a first reflector (110), and a second reflector (120). The active layer (130) performs light emission by current injection. The first reflector (110) and the second reflector (120) are stacked in a first direction with the active layer (130) interposed therebetween. The separation groove (152) is provided symmetrically around the light emission section (Em) on an emission surface of light from the stack structure (100) in the first direction. The separation groove (152) is dug in the stack structure (100) in the first direction. The high resistance region (Hr) is provided in the stack structure (100) on the outer side of an outermost shape of the separation groove (152) on the emission surface. The high resistance region (Hr) has electrical resistance higher than that of the light emission section (Em).

An edge-emitting GaAs-based semiconductor laser uses a tunnel junction in combination with an inverted p-n junction to address oxidation problems associated with the use of a high aluminum content p-type cladding arrangement. In particular, a tunnel junction is formed on an n-type GaAs substrate, with p-type cladding and waveguiding layers formed over the tunnel junction. N-type waveguiding and cladding layers are thereafter grown on top of the active region. Since the p-type layers are positioned below the active region and not exposed to air during processing, a relative high aluminum content may be used, which improves the thermal and electrical properties of the device. Since the n-type material does not require a high aluminum content, it may be further processed to form a ridge structure without introducing any substantial oxidation of the structure.

A semiconductor device includes a substrate comprising a layer made of Ge and a semiconductor multilayer structure grown on the layer made of Ge. The semiconductor multilayer structure includes at least one first layer comprising a material selected from a group consisting of Al.sub.xGa.sub.1-xAs, Al.sub.xGa.sub.1-x-yIn.sub.yAs, Al.sub.xGa.sub.1-x-yIn.sub.yAs.sub.1-zP.sub.z, Al.sub.xGa.sub.1-x-yIn.sub.yAs.sub.1-zN.sub.z, and Al.sub.xGa.sub.1-x-yIn.sub.yAs.sub.1-z-cN.sub.zP.sub.c, Al.sub.xGa.sub.1-x-yIn.sub.yAs.sub.1-z-cN.sub.zSb.sub.c, and Al.sub.xGa.sub.1-x-yIn.sub.yAs.sub.1-z-cP.sub.zSb.sub.c, wherein for any material a sum of the contents of all group-III elements equals 1 and a sum of the contents of all group-V elements equals 1. The semiconductor multilayer structure also includes at least one second layer comprising a material selected from a group consisting of GaInAsNSb, GaInAsN, AlGaInAsNSb, AlGaInAsN, GaAs, GaInAs, GaInAsSb, GaInNSb, GaInP, GaInPNSb, GaInPSb, GaInPN, AlInP, AlInPNSb, AlInPN, AlInPSb, AlGaInP, AlGaInPNSb, AlGaInPN, AlGaInPSb, GaInAsP, GaInAsPNSb, GaInAsPN, GaInAsPSb, GaAsP, GaAsPNSb, GaAsPN, GaAsPSb, AlGaInAs and AlGaAs.

A laser diode package includes a heat pipe having a fluid chamber enclosed in part by a heat exchange wall for containing a fluid. Wicking channels in the fluid chamber is adapted to wick a liquid phase of the fluid from a condensing section of the heat pipe to an evaporating section of the heat exchanger, and a laser diode is connected to the heat exchange wall at the evaporating section of the heat exchanger so that heat produced by the laser diode is removed isothermally from the evaporating section to the condensing section by a liquid-to-vapor phase change of the fluid.

An optical device includes a first array of emitters disposed on a substrate and configured to emit respective beams of optical radiation in a direction perpendicular to the substrate. A second array of microlenses is positioned on the substrate in alignment with the respective beams of the emitters, having respective sag profiles that vary over an area of the substrate. The second array includes at least first microlenses in a central region of the substrate and second microlenses in a peripheral region of the substrate, such that the first microlenses have respective first focal powers, while the second microlenses have respective second focal powers, which are less than the first focal powers.

A pyrolytic graphite (PG) substrate and laser diode package includes a substrate body having a PG crystalline structure with a basal plane oriented at a pre-determined orientation angle as measured from a longitudinal axis of a heat generating material, such as a laser diode, mounted on a surface of the PG substrate, so that a coefficient of thermal expansion (CTE) of the PG substrate is substantially matched with a CTE of the material.

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 μm and the edge regions includes at least a minimum width. The minimum width is 3 μm 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 adjoining the central region and beyond the central region.

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.

A semiconductor device includes a substrate comprising a layer made of Ge and a semiconductor multilayer structure grown on the layer made of Ge. The semiconductor multilayer structure includes at least one first layer comprising a material selected from a group consisting of Al.sub.xGa.sub.1-xAs, Al.sub.xGa.sub.1-x-yIn.sub.yAs, Al.sub.xGa.sub.1-x-yIn.sub.yAs.sub.1-zP.sub.z, Al.sub.xGa.sub.1-x-yIn.sub.yAs.sub.1-zN.sub.z, and Al.sub.xGa.sub.1-x-yIn.sub.yAs.sub.1-z-cN.sub.zP.sub.c, Al.sub.xGa.sub.1-x-yIn.sub.yAs.sub.1-z-cN.sub.zSb.sub.c, and Al.sub.xGa.sub.1-x-yIn.sub.yAs.sub.1-z-cP.sub.zSb.sub.c, wherein for any material a sum of the contents of all group-III elements equals 1 and a sum of the contents of all group-V elements equals 1. The semiconductor multilayer structure also includes at least one second layer comprising a material selected from a group consisting of GaInAsNSb, GaInAsN, AlGaInAsNSb, AlGaInAsN, GaAs, GaInAs, GaInAsSb, GaInNSb, GaInP, GaInPNSb, GaInPSb, GaInPN, AlInP, AlInPNSb, AlInPN, AlInPSb, AlGaInP, AlGaInPNSb, AlGaInPN, AlGaInPSb, GaInAsP, GaInAsPNSb, GaInAsPN, GaInAsPSb, GaAsP, GaAsPNSb, GaAsPN, GaAsPSb, AlGaInAs and AlGaAs.

A pyrolytic graphite (PG) substrate and laser diode package includes a substrate body having a PG crystalline structure with a basal plane oriented at a pre-determined orientation angle as measured from a longitudinal axis of a heat generating material, such as a laser diode, mounted on a surface of the PG substrate, so that a coefficient of thermal expansion (CTE) of the PG substrate is substantially matched with a CTE of the material.