A quantum cascade laser includes a semiconductor substrate and an active layer having a cascade structure, in which unit layered bodies, each composed of a quantum well light emitting layer and an injection layer, are stacked, wherein the unit layered body has a subband level structure having an upper laser level, a lower laser level, and a relaxation miniband composed of at least two energy levels with an energy spacing smaller than the energy difference (E.sub.UL) between the upper laser level and the lower laser level, the energy width of the relaxation miniband is smaller than the energy (E.sub.LO−E.sub.UL) obtained by subtracting the energy difference (E.sub.UL) from the energy (E.sub.LO) of longitudinal optical phonons, and electrons subjected to the intersubband transition are relaxed in the relaxation miniband and are injected into a quantum well light emitting layer in a subsequent unit layered body.

A semiconductor stack includes a first-conductivity-type layer, a quantum well structure, and a second-conductivity-type layer. The first-conductivity-type layer, the quantum well structure, and the second-conductivity-type layer are stacked in this order. The quantum well structure includes a first semiconductor layer, a second semiconductor layer, and a third semiconductor layer. In the first semiconductor layer and the third semiconductor layer, compositions of the first semiconductor layer and the third semiconductor layer are changed such that a bandgap decreases toward the second semiconductor layer. Transition of an electron is possible between a conduction band of each of the first semiconductor layer and the third semiconductor layer and a valence band of the second semiconductor layer.

An embodiment relates to a surface emitting laser device and a light emitting device including the same. A surface emitting laser device according to the embodiment may include a first reflective layer; an active layer disposed on the first reflective layer; an aperture area disposed on the active layer and including an aperture and an insulating region; and a second reflective layer disposed in the aperture area. The active layer may comprise a plurality of quantum wells, quantum barriers, and intermediate layers disposed between the quantum wells and the quantum barriers. The quantum wells and the quantum barriers may include a ternary material, and the intermediate layers may comprise a binary material.

UV laser devices, systems, and methods are shown and/or described herein. Included are a method, device or system for VECSEL and MECSEL lasers including both barrier-pumped and in-well pumped lasers. Also disclosed is a method of manufacturing gain chips for use in the lasers, arrangements of lasers, and selection of proper non-linear crystal (NLC) for use in the device.

A semiconductor light source is disclosed. In one embodiment, a semiconductor light source includes at least one semiconductor laser configured to generate a primary radiation and at least one conversion element configured to generate a longer-wave visible secondary radiation from the primary radiation, wherein the conversion element includes a semiconductor layer sequence having one or more quantum well layers, wherein, in operation, the primary radiation is irradiated into the semiconductor layer sequence parallel to a growth direction thereof, with a tolerance of at most 15°, wherein, in operation, the semiconductor layer sequence is homogeneously illuminated with the primary radiation, and wherein a growth substrate of the semiconductor layer sequence is located between the semiconductor layer sequence and the semiconductor laser, the growth substrate being oriented perpendicular to the growth direction.

According to embodiments of the present invention, a laser source is provided. The laser source includes a photonic crystal structure including a first domain having a plurality of first holes defined therein, the first domain being associated with a first set of Chern numbers, and a second domain having a plurality of second holes defined therein, the second domain being associated with a second set of Chern numbers, wherein the plurality of first holes and the plurality of second holes are arranged to define an interface region between the first domain and the second domain, the interface region defining an optical cavity for lasing. According to further embodiments of the present invention, a method for forming a laser source is also provided.

Quantum well designs for tunable VCSELs are disclosed that are tolerant of the wavelength shift. Specifically, the active region has even number of substantially uniformly spaced (¼ of the center wavelength in the semiconducting material) quantum wells.

Stacked edge-emitting lasers having multiple active regions coupled together using tunnel junctions. The composition of each of the active regions (quantum wells and/or barriers) differs to provide a controlled different emission wavelength for each junction, when each junction is individually operated at the same fixed temperature. When the device is under operation, a thermal gradient exists across the junctions, and the emission wavelengths of each junction coincide as the different temperature for each junction causes relative wavelength shifts. Thus, the effect of temperature on the emission wavelength of the device is compensated for, producing a narrower linewidth emission.

The invention relates to an apparatus, system and method for reducing or eliminating polarization effects in a compound semiconductor quantum well optical gain structure including the quantum confined Stark effect (QCSE) and carrier leakage effects. The system comprises a quantum well formed by a monotonic, stepwise and/or continuous compositional grading of a first quantum well interface toward a reduced bandgap, also including a monotonic, stepwise or continuous compositional grading of a second quantum well interface toward an increased bandgap thereby creating a quantum well shape that is substantially symmetric under the influence of electrostatic and/or electrodynamic fields. The system also comprises an electron blocking layer formed by a stepwise or continuous compositional grading starting from the maximum bandgap of the quantum well and increasing toward a larger bandgap, thereby creating a barrier shape with reduced electron sheet charge due to the influence of electrostatic fields.

A semiconductor light-emitting device includes a layer structure of a nitride semiconductor, and the layer structure includes an n-type semiconductor layer, a p-type semiconductor layer, and an intermediate layer. The intermediate layer includes an active layer and is provided between the n-type semiconductor layer and the p-type semiconductor layer. The layer structure includes a residual donor in a region at least included in the intermediate layer, the region being situated between the active layer and the p-type semiconductor layer. The intermediate layer includes impurities in the region between the active layer and the p-type semiconductor layer, the impurities compensating the residual donor. Further, the intermediate layer is configured such that a concentration of the impurities in the region between the active layer and the p-type semiconductor layer is higher than a concentration of the impurities in the p-type semiconductor layer.