A laser diode (1) includes an AlN single crystal substrate (11), an n-type cladding layer (12) formed on the substrate and including a nitride semiconductor layer having n-type conductivity, a light-emitting layer (14) formed on the n-type cladding layer and including one or more quantum wells, a p-type cladding layer (20) formed on the light-emitting layer and including a nitride semiconductor layer having p-type conductivity, and a p-type contact layer (18) formed on the p-type cladding layer and including a nitride semiconductor that includes GaN. The p-type cladding layer includes a p-type longitudinal conduction layer (16) that includes Al.sub.sGa.sub.1−sN (0.3≤s≤1), has a composition gradient such that the Al composition s decreases with increased distance from the substrate, and has a film thickness of less than 0.5 μm, and a p-type transverse conduction layer (17) that includes Al.sub.tGa.sub.1−tN (0<t≤1).

An optoelectronic semiconductor device is disclosed wherein the device is a vertical-cavity surface-emitting laser or a photodiode containing a section, the top part of which is electrically isolated from the rest of the device. The electric isolation can be realized by etching a set of holes and selective oxidation of AlGaAs layer or layers such that the oxide forms a continuous layer or layers everywhere beneath the top surface of this section. Alternatively, a device can be grown epitaxially on a semi-insulating substrate, and a round trench around a section of the device can be etched down to the semi-insulating substrate thus isolating this section electrically from the rest of the device. Then if top contact pads are deposited on top of the electrically isolated section, the pads have a low capacitance, and a pad capacitance below two hundred femto-Farads, and the total capacitance of the device below three hundred femto-Farads can be reached.

Novel ICL layering designs, ridge waveguide architectures, and processing protocols that will significantly lower the optical losses and improve the power conversion efficiencies of interband cascade lasers designed for both DFB single-mode and high-power applications. The semiconductor top cladding and metal contact layers are eliminated or significantly reduced. By instead using a dielectric or air top clad, or dielectric or air layers to supplement a thin top clad, in conjunction with lateral current injection and weak index-guiding, the present invention will substantially reduce the internal loss of such ICLs, resulting in lower lasing threshold, higher efficiency, and higher maximum power.

In an embodiment a semiconductor laser component includes a plurality of semiconductor lasers, each of the semiconductor lasers configured to emit primary electromagnetic radiation of a primary spectral bandwidth in a visible wavelength range and a beam combiner configured to combine the primary electromagnetic radiations emitted from the semiconductor lasers, form secondary electromagnetic radiation from a superposition of the primary electromagnetic radiations of the semiconductor lasers and couple the secondary electromagnetic radiation out from the beam combiner, wherein the secondary electromagnetic radiation has a secondary spectral bandwidth that is at least twice as large as an average value of the primary spectral bandwidths.

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.

A semiconductor light-emitting device including a light-emitting layer, a first N-type waveguide layer and a plurality of semiconductor layers is provided. The light light-emitting layer has a first side and a second side opposite to the first side. The first N-type waveguide layer is disposed at the first side, and the semiconductor layers are disposed at the second side. The semiconductor layers include at least one P-type semiconductor layer and a plurality of N-type semiconductor layers, and a quantity of the N-type semiconductor layers is more than a quantity of the at least one P-type semiconductor layer.

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.

An edge-emitting semiconductor laser includes: a semiconductor substrate; a first cladding layer having a first refractive index and formed on the semiconductor substrate; an active layer formed on the first cladding layer and having a second refractive index higher than the first refractive index; a Bragg reflector formed on the active layer and in which low-refractive-index layers and high-refractive-index layers each having a thickness larger than λ/4n are alternately laid one on another where λ is an lasing wavelength and n is a refractive index of a medium; a light absorption layer formed on the Bragg reflector and having bandgap energy lower than that of the active layer; and a second cladding layer formed on the light absorption layer and having a third refractive index lower than the second refractive index.

A semiconductor laser device having a diffraction grating is disclosed. The semiconductor laser device comprises a first diffraction grating provided on a substrate, a second diffraction grating continuous to one end of the first diffraction grating along an optical waveguide direction, and an active layer provided above the first diffraction grating. The second diffraction grating has a pitch 1.05 times or greater, or 0.95 times or smaller of the pitch of the first diffraction grating.

The invention describes a Vertical Cavity Surface Emitting Laser and a method of manufacturing such a Vertical Cavity Surface Emitting Laser. The Vertical Cavity Surface Emitting Laser comprising a first electrical contact (105, 405, 505, 605, 705), a substrate (110, 410, 610, 710), a first distributed Bragg reflector (115, 415, 615, 715), an active layer (120, 420, 620, 720), a distributed heterojunction bipolar phototransistor (125, 425, 625, 725), a second distributed Bragg reflector (130, 430, 630, 730) and a second electrical contact (135, 435, 535, 635, 735), the distributed heterojunction bipolar phototransistor (125, 425, 625, 725) comprising a collector layer (125a), a light sensitive layer (125c), a base layer (125e) and an emitter layer (125f), wherein the distributed heterojunction bipolar phototransistor (125, 425, 625, 725) is arranged such that there is an optical coupling between the active layer (120, 420, 620, 720) and the distributed heterojunction bipolar phototransistor (125, 425, 625, 725) for providing an active carrier confinement by means of the distributed heterojunction bipolar phototransistor (125, 425, 625, 725) such that an optical mode of the Vertical Cavity Surface Emitting Laser is self-positioning in accordance with the active carrier confinement during operation of the Vertical Cavity Surface Emitting Laser. It is the intention of the present invention to provide a VCSEL which can be easily and reliably processed by integrating the distributed heterojunction bipolar phototransistor (125, 425, 625, 725).