A vertical cavity surface emitting laser (VCSEL) has first and second electrical contacts, and an optical resonator. The optical resonator has first and second distributed Bragg reflectors (DBRs), an active layer, a distributed heterojunction bipolar phototransistor (DHBP), and an optical guide. The DHBP has a collector layer, light sensitive layer; a base layer; and an emitter layer. There is an optical coupling between the active layer and the DHBP for providing an active carrier confinement by the DHBP. The optical guide guides an optical mode within the optical resonator during operation. The optical guide is outside a current flow which can be provided by the first and second electrical contacts during operation of the VCSEL. The optical guide is outside a layer sequence between the first and second electrical contacts in the vertical direction of the VCSEL. The optical guide has an oxide aperture arranged in the second DBR.

Provided is an optical semiconductor device including a laminate structural body 20 in which an n-type compound semiconductor layer 21, an active layer 23, and a p-type compound semiconductor layer 22 are laminated in this order. The active layer 23 includes a multiquantum well structure including a tunnel barrier layer 33, and a compositional variation of a well layer 31.sub.2 adjacent to the p-type compound semiconductor layer 22 is greater than a compositional variation of another well layer 31.sub.1. Band gap energy of the well layer 31.sub.2 adjacent to the p-type compound semiconductor layer 22 is smaller than band gap energy of the other well layer 31.sub.1. A thickness of the well layer 31.sub.2 adjacent to the p-type compound semiconductor layer 22 is greater than a thickness of the other well layer 31.sub.1.

The invention relates to, inter alia, a light-emitting semiconductor component comprising the following: a first mirror (102, 202, 302, 402, 502), a first conductive layer (103, 203, 303, 403, 503), a light-emitting layer sequence (104, 204, 304, 404, 504) on a first conductive layer face facing away from the first mirror, anda second conductive layer (105, 205, 305, 405, 505) on a light-emitting layer sequence face facing away from the first conductive layer, whereinthe first mirror, the first conductive layer, the light-emitting layer sequence, and the second conductive layer are based on a III-nitride compound semiconductor material, the first mirror is electrically conductive, andthe first mirror is a periodic sequence of homoepitaxial materials with varying refractive indices.

A surface emitting quantum cascade laser includes an active layer and a first semiconductor layer. The active layer includes a plurality of quantum well layers and is capable of emitting laser light by intersubband transition. The first surface includes an internal region and an outer peripheral region. Grating pitch of the first pits is m times grating pitch of the second pits. The outer peripheral region surrounds the internal region. A first planar shape of an opening end of the first pit is asymmetric with respect to a line passing through barycenter of the first planar shape and is parallel to at least one side of the first two-dimensional grating. A second planar shape of an opening end of the second pit is symmetric with respect to each of lines passing through barycenter of the second planar shape and is parallel to either side of the second two-dimensional grating.

A group III-nitride semiconductor device comprises a light emitting semiconductor structure comprising a p-type layer and an n-type layer operable as a light emitting diode or laser. On top of the p-type layer there is arranged an n+ or n++-type layer of a group III-nitride, which is transparent to the light emitted from the underlying semiconductor structure and of sufficiently high electrical conductivity to provide lateral spreading of injection current for the light-emitting semiconductor structure.

To provide a high-quality group III nitride semiconductor. A group III nitride semiconductor including an n-GaN layer composed of Al.sub.xGa.sub.1xN(0x<1), an InGaN layer disposed on the n-GaN layer and composed of InGaN, an n-AlGaN layer disposed on the InGaN layer and composed of n-type Al.sub.yGa.sub.1yN (0y<1), and a functional layer disposed on the n-AlGaN layer, wherein the concentration of Mg in the n-GaN layer is higher than the concentration of Mg in the n-AlGaN layer.

A distributed feedback (DFB) 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. The DFB laser includes a separate confinement heterostructure layer positioned between the quantum well active layer and then-type cladding layer. The DFB laser includes an electric-field-distribution-control layer positioned between the separate confinement heterostructure layer and then-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 DFB laser has a function to select a specific wavelength by returning a specific wavelength in the wavelength-variable laser.

Edge-emitting laser diodes having high confinement factors and lattice-matched, porous cladding layers are described. The laser diodes may be formed from layers of III-nitride material. A cladding layer may be electrochemically etched to form a porous cladding layer having a high refractive index contrast with an active junction of the device. A transparent conductive oxide layer may be deposited to form a top-side cladding layer with high refractive index contrast and low resistivity.

A semiconductor laser diode includes multiple layers stacked along a first direction, in which the multiple layers include: a first multiple of semiconductor layers; an optical waveguide on the first multiple of semiconductor layers, in which the optical waveguide includes a semiconductor active region for generating laser light, and in which the optical waveguide defines a resonant cavity having an optical axis; and a second multiple of semiconductor layers on the optical waveguide region, in which a resistivity profile of at least one layer of the multiple layers varies gradually between a maximum resistivity and a minimum resistivity along a second direction extending orthogonal to the first direction, in which a distance between the maximum resistivity and the minimum resistivity is greater than at least about 2 microns.

A vertical cavity surface emitting laser includes an active layer having a quantum well structure, a first laminate for a first distributed Bragg reflector, and a first spacer region provided between the active layer and the first laminate. A barrier layer of the quantum well structure includes a first compound semiconductor containing aluminum as a group m constituent element. The first spacer region includes a second compound semiconductor having a larger aluminum composition than the first compound semiconductor. A concentration of first dopant in the first laminate is larger than a concentration of the first dopant in the first portion of the first spacer region. The concentration of the first dopant in the first portion of the first spacer region is larger than a concentration of the first dopant in the second portion of the first spacer region.