A semiconductor structure can comprise a plurality of first semiconductor layers comprising wide bandgap semiconductor layers, a narrow bandgap semiconductor layer, and a chirp layer between the plurality of first semiconductor layers and the narrow bandgap semiconductor layer. The values of overlap integrals between different electron wavefunctions in a conduction band of the chirp layer can be less than 0.05 for intersubband transition energies greater than 1.0 eV, and/or the values of overlaps between electron wavefunctions and barrier centers in a conduction band of the chirp layer can be less than 0.3 nm.sup.−1, when the structure is biased at an operating potential. The chirp layer can comprise a short-period superlattice with alternating wide bandgap barrier layers and narrow bandgap well layers, wherein the thickness of the barrier layers, or the well layers, or the thickness of both the barrier and well layers changes throughout the chirp layer.

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.

An embodiment relates to a surface-emitting laser device and a light-emitting device including same. A surface-emitting laser device according to the embodiment can include: a first reflective layer; an active area disposed on the first reflective layer; an aperture area disposed on the active area; and a second reflective layer disposed on the aperture area. The second reflective layer can include: a first AlGaAs-based layer comprising Al.sub.x1Ga.sub.(1-x1)As (wherein 0<X1<0.2); a second AlGaAs-based layer disposed on the first AlGaAs-based layer and comprising Al.sub.x2Ga.sub.(1-x2)As (wherein 0.8<X2<1.0); and an AlGaAs-based transition area disposed between the first AlGaAs-based layer and the second AlGaAs-based layer. The AlGaAs-based transition area can include: a third AlGaAs-based layer comprising Al.sub.x3Ga.sub.(1-x3)As (wherein 0<X3<0.2); and a fourth AlGaAs-based layer comprising Al.sub.x4Ga.sub.(1-x4)As (wherein 0.8<X4<1.0).

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 semiconductor structure can comprise a plurality of first semiconductor layers comprising wide bandgap semiconductor layers, a narrow bandgap semiconductor layer, and a chirp layer between the plurality of first semiconductor layers and the narrow bandgap semiconductor layer. The values of overlap integrals between different electron wavefunctions in a conduction band of the chirp layer can be less than 0.05 for intersubband transition energies greater than 1.0 eV, and/or the values of overlaps between electron wavefunctions and barrier centers in a conduction band of the chirp layer can be less than 0.3 nm.sup.−1, when the structure is biased at an operating potential. The chirp layer can comprise a short-period superlattice with alternating wide bandgap barrier layers and narrow bandgap well layers, wherein the thickness of the barrier layers, or the well layers, or the thickness of both the barrier and well layers changes throughout the chirp layer.

A semiconductor structure can comprise a plurality of first semiconductor layers comprising wide bandgap semiconductor layers, a narrow bandgap semiconductor layer, and a chirp layer between the plurality of first semiconductor layers and the narrow bandgap semiconductor layer. The values of overlap integrals between different electron wavefunctions in a conduction band of the chirp layer can be less than 0.05 for intersubband transition energies greater than 1.0 eV, and/or the values of overlaps between electron wavefunctions and barrier centers in a conduction band of the chirp layer can be less than 0.3 nm.sup.1, when the structure is biased at an operating potential. The chirp layer can comprise a short-period superlattice with alternating wide bandgap barrier layers and narrow bandgap well layers, wherein the thickness of the barrier layers, or the well layers, or the thickness of both the barrier and well layers changes throughout the chirp layer.

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.

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.min<x1.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.

The present disclosure relates to a glass having a refractive index of at least 1.7 as well as the use of the glass as a cladding glass of a solid-state laser. The disclosure also relates to a laser component comprising a core of doped sapphire and a cladding glass being placed on said core. The cladding glass is arranged on said core such that light exiting from the core due to parasitic laser activity can enter the cladding glass and can be absorbed there. Thus, a laser component with improved efficiency is obtained. The present disclosure also relates to a method for producing the laser component.

An electrically pumped surface-emitting photonic crystal laser has a second surface of a first metal electrode arranged on a photonic crystal structure, a first electrical currents confining structure and a filled layer, and a substrate having a top surface arranged on a first surface of the first metal electrode for the photonic crystal structure to be inversely disposed. The photonic crystal laser has its epitaxy structure etched from above to fabricate the photonic crystal to allow laser beams to be reflected by the first metal electrode due to the inverse disposition and to be emitted from a rear surface of the epitaxy structure.