An optical semiconductor device outputting a predetermined wavelength of laser light includes a quantum well active layer positioned between a p-type cladding layer and an n-type cladding layer in thickness direction. The optical semiconductor device includes a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer. The optical semiconductor device further includes an electric-field-distribution-control layer positioned between the separate confinement heterostructure layer and the n-type cladding layer and configured by at least two semiconductor layers having band gap energy greater than band gap energy of a barrier layer constituting the quantum well active layer. The optical semiconductor device is applied to a ridge-stripe type laser.

An improved structure for reducing compound semiconductor wafer distortion comprises a contact metal layer, at least one stress balance layer and a die attachment layer. The contact metal layer is formed on a bottom surface of a compound semiconductor wafer; the at least one stress balance layer is formed on a bottom surface of the contact metal layer, wherein the at least one stress balance layer is made of at least one conductive material; the die attachment layer is formed on a bottom surface of the at least one stress balance layer, wherein the die attachment layer is made of conductive material. By locating the at least one stress balance layer between the contact metal layer and the die attachment layer, the stress suffered by the compound semiconductor wafer is balanced so that the distortion of the compound semiconductor wafer is reduced.

A wavelength-variable laser outputting a predetermined wavelength of laser light includes: a quantum well active layer positioned between a p-type cladding layer and an n-type cladding layer in thickness direction; a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer; and an electric-field-distribution-control layer positioned between the separate confinement heterostructure layer and the n-type cladding layer and configured by at least two semiconductor layers having band gap energy greater than band gap energy of a barrier layer constituting the quantum well active layer.

An active layer of a quantum cascade laser includes an active layer includes a plurality of emission regions and a plurality of injection regions. Each emission region includes an injection barrier layer, and an light-emitting quantum well layer that has at least two well layers, and that emits infrared light by undergoing an intersubband transition. Each injection region includes an extraction barrier layer, and a relaxation quantum well layer that creates an energy level for relaxing the energy of carriers from the each emission region. One of adjacent two well layers in the light-emitting quantum well layer of the each emission region on the side of the extraction barrier layer is deeper than a second well layer on the side of the injection barrier layer. The each emission region and the injection region are alternately stacked.

A semiconductor laser may include a substrate, a multi quantum well (MQW) active layer, and an electron stopper layer. The MQW active layer may include a quantum well that is tensile strained and a barrier that is compressively strained. The barrier may be formed from an aluminum gallium indium arsenide phosphide alloy having a first Al.sub.xGa.sub.yIn.sub.(1-x-y)As.sub.zP.sub.(1-z) composition. The electron stopper layer may include an aluminum gallium indium arsenide phosphide alloy having a second Al.sub.xGa.sub.yIn.sub.(1-x-y)As.sub.zP.sub.(1-z) composition.

An optical semiconductor device outputting a predetermined wavelength of laser light includes: a quantum well active layer positioned between a p-type cladding layer and an n-type cladding layer in thickness direction; a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer; and an electric-field-distribution-control layer positioned between the separate confinement heterostructure layer and the n-type cladding layer and configured by at least two semiconductor layers having band gap energy greater than band gap energy of a barrier layer constituting the quantum well active layer.

A semiconductor laser diode (LD) having an optical grating is disclosed. The LD includes a lower cladding layer that buries the optical grating, an active layer, and an upper cladding layer. The active layer has the multi-quantum well (MQW) structure of barrier layers and well layers alternately arranged to each other. The MQW structure further includes intermediate layers between the barrier layers and the well layers, and have lattice constant between that of the barrier layer and that of the well layer. The inter mediate layer has a thickness thinner than 1 nm.

A light emitting element according to the present disclosure includes: a GaN substrate; a first strain correction layer disposed above the GaN substrate and including In.sub.xGa.sub.1-xN of a first conductivity type where x is greater than 0 and less than or equal to 1; a first low refractive index layer disposed above the first strain correction layer, including In.sub.1-a-bGa.sub.aAl.sub.bN of the first conductivity type, and having relationships of (a/0.98)+(b/0.8)1, (a/1.02)+(b/0.85)1, and (a/1.03)+(b/0.68)1; a first clad layer disposed above the first low refractive index layer, including Al.sub.xGa.sub.1-xN of the first conductivity type where z is greater than or equal to 0.03 and less than or equal to 0.06, and having a refractive index higher than a refractive index of the first low refractive index layer; and an active layer disposed above the first clad layer.

A vertical cavity surface emitter device (e.g., VCSEL or RC-LED) containing a buried index-guiding current confinement aperture layer which is grown, and lithographically processed to define position, shape and dimension of an inner aperture. In a regrowth process, the aperture is filled with a single crystalline material from the third contact layer. The aperture provides for both current and optical confinement, while allowing for higher optical power output and improved thermal conductivity.

Externally-strained devices such as LED and FET structures as discussed herein may have strain applied before or during their being coupled to a housing or packaging substrate. The packaging substrate may also be strained prior to receiving the structure. The strain on the devices enables modulation of light intensity, color, and electrical currents in some embodiments, and in alternate embodiments, enables a fixed strain to be induced and maintained in the structures.