A semiconductor laser including an active zone and a waveguide, wherein the active zone includes an active layer configured to generate electromagnetic radiation during operation of the semiconductor laser, the waveguide is configured to guide the electromagnetic radiation generated during operation of the semiconductor laser within the semiconductor laser, the waveguide includes a subregion formed from a compound semiconductor material, wherein a proportion of a material of the compound semiconductor material gradually increases in the entire subregion along the vertical direction toward the active zone so that a refractive index of the subregion gradually decreases toward the active zone, and the proportion is an aluminum proportion or a phosphorus proportion.

This invention aims at providing a nitride semiconductor causing no element breakdown even in driving under a high current density.

A nitride semiconductor element is provided with a nitride semiconductor active layer made of Al.sub.xGa.sub.(1-x)N and a composition change layer made above the nitride semiconductor active layer and made of Al.sub.x3Ga.sub.(1-x3)N in which an Al composition ratio x3 decreases in a direction away from the nitride semiconductor active layer. The composition change layer has a first composition change region having a thickness larger than 0 nm and smaller than 400 nm and a second composition change region which is a region further away from the nitride semiconductor active layer than the first composition change region and in which the change rate of the Al composition ratio x3 in the thickness direction of the film thickness of the composition change layer is higher than that of the first composition change region, in which, in the first composition change region, the Al composition ratio continuously changes in the thickness direction of the film thickness.

Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted along with photoluminescence spectroscopy (i.e. fluorescence and/or phosphorescence spectroscopy) to provide high levels of sensitivity and specificity in the same instrument.

A semiconductor laser element includes an n-side semiconductor layer, an active layer, and a p-side semiconductor layer. A least a portion of the p-side semiconductor layer forms a ridge projecting upward. The p-side semiconductor layer includes an undoped first part, an electron barrier layer containing a p-type impurity and having a larger band gap energy than the first part, and a second part having at least one p-type semiconductor layer. The first part includes an undoped p-side composition graded layer in which a band gap energy increases towards the electron barrier layer, and an undoped p-side intermediate layer disposed on or above the p-side composition graded layer. A lower end of the ridge is positioned at the p-side intermediate layer.

A laser diode having a semiconductor layer sequence based on a nitride compound semiconductor material includes an n-type cladding layer, a first waveguide layer, a second waveguide layer and an active layer, and a p-type cladding layer including a first partial layer and a second partial layer, wherein the first partial layer includes Al.sub.x1Ga.sub.1-x1N with 0x11 or Al.sub.x1In.sub.y1Ga.sub.1-x1-y1N with 0x11, 0y1<1 and x1+y11, the aluminum content x1 decreases in a direction pointing away from the active layer so that the aluminum content has a maximum value x1.sub.max and a minimum value x1.sub.minx1.sub.max, and the second partial layer includes Al.sub.x2Ga.sub.1-x2N with 0x2x1.sub.min or Al.sub.x2In.sub.y2Ga.sub.1-x2-y2N with 0x2x1.sub.min, 0y2<1 and x2+y21.

A vertical cavity surface emitting laser includes a first laminate including first semiconductor layers having a first Al composition, and second semiconductor layers having a second Al composition greater than the first Al composition; a current confinement structure including a current aperture and a current blocker; a first compound semiconductor layer adjacent to the current confinement structure; and a second compound semiconductor layer adjacent to the first laminate and the first compound semiconductor layer. The first compound semiconductor layer has a first aluminum profile changing monotonously in a direction from the first laminate to the current confinement structure from a first minimum Al composition within a range greater than the first Al composition and smaller than the second Al composition to a first maximum Al composition. The second compound semiconductor layer has an Al composition greater than the first Al composition and smaller than the first maximum Al composition.

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.

The present technology provides a surface emitting laser capable of reducing a voltage drop at a tunnel junction.

The present technology provides a surface emitting laser including: first and second multilayer film reflectors (102, 112) laminated together; a plurality of active layers laminated together between the first and second multilayer film reflectors (102, 112); and a tunnel junction (107) disposed between first and second active layers (104, 110) adjacent to each other in a lamination direction among the plurality of active layers, in which the tunnel junction (107) includes an n-type semiconductor layer (107b) and a p-type semiconductor layer (107a) laminated together, and the p-type semiconductor layer (107a) includes first and second p-type semiconductor regions (107a1, 107a2) laminated together.

An object of the present invention is to provide a method for manufacturing an optical device having a laser diode, which method is suitable for mass production, and an optical device having a laser diode which allows accurate property evaluations thereof with small measurement errors. Specifically, the method includes: an etching process of etching a semiconductor lamination unit to form a mesa structure having a resonator end face, thereby forming a laser diode; and a reflecting layer forming process of forming a light reflecting layer such that the light reflecting layer covers entire side surfaces of the mesa structure, wherein the semiconductor lamination unit has a substate, a n-type clad layer including a nitride semiconductor layer having n-type conductivity, a light-emitting layer including at least one quantum well, and a p-type clad layer including a nitride semiconductor layer having p-type conductivity, laminated in this order.

Laser diodes are configured to suppress lasing of a first and higher order modes along a fast axis of an optical beam emitted by the laser diode. An optical cavity is defined by a p-side of the laser diode, an n-side of the laser diode, and an active region located between the p- and n-sides. The n-side has an n-waveguide layer forming at least a portion of a waveguide having a quantum well offset towards the p-side. According to some embodiments, double cladding layers out-couple higher order modes. According to other embodiments, double waveguides (e.g., symmetric and asymmetric) reduce gain applied to higher order modes.