In a semiconductor laser according to an embodiment of the present disclosure, a ridge part has a structure in which a plurality of gain regions and a plurality of Q-switch regions are each disposed alternately with each of separation regions being interposed therebetween in an extending direction of the ridge part. The separation regions each have a separation groove that separates from each other, by a space, the gain region and the Q-switch region adjacent to each other. The separation groove has a bottom surface at a position, in a second semiconductor layer, higher than a part corresponding to a foot of each of both sides of the ridge part.

In an example, the present invention provides a method for fabricating a light emitting device configured as a Group III-nitride based laser device. The method also includes forming a gallium containing epitaxial material overlying the surface region of a substrate member. The method includes forming a p-type (Al,In,Ga)N waveguiding material overlying the gallium containing epitaxial material under a predetermined process condition. The method includes maintaining the predetermined process condition such that an environment surrounding a growth of the p-type (Al,In,Ga)N waveguide material is substantially a molecular N.sub.2 rich gas environment. The method includes maintaining a temperature ranging from 725 C to 925 C during the formation of the p-type (Al,In,Ga)N waveguide material, although there may be variations. In an example, the predetermined process condition is substantially free from molecular H.sub.2 gas.

A quantum cascade laser device includes a semiconductor substrate, an active layer provided on the semiconductor substrate, and an upper clad layer provided on a side of the active layer opposite to the semiconductor substrate side and having a doping concentration of impurities of less than 1?10.sup.17 cm.sup.?3. Unit laminates included in the active layer each include a first emission upper level, a second emission upper level, and at least one emission lower level in their subband level structure. The active layer is configured to generate light having a center wavelength of 10 ?m or more due to electron transition between at least two levels of the first emission upper level, the second emission upper level, and the at least one emission lower level in the light emission layer in each of the unit laminates.

An embodiment relates to a surface-emitting laser element, a light-emitting device comprising same, and a method for manufacturing same. A surface-emitting laser element according to an embodiment may comprise: a substrate; a first reflective layer disposed on the substrate; an active layer disposed on the first reflective layer; an aperture region disposed on the active layer and including an aperture and an insulation region; and a second reflective layer disposed on the aperture region. The doping level of the aperture region may be (X+3)?XE18 (atoms/cm.sup.3) A ratio (b/a) of a second minimum diameter (b) to a first maximum diameter (a) of the aperture may be [95.0?(2X/3)]% to [99.9?(X/3)]%, wherein X may be 0 to 3.

Embodiments of the invention include a III-nitride light emitting layer disposed between an n-type region and a p-type region, a III-nitride layer including a nanopipe defect, and a nanopipe terminating layer disposed between the III-nitride light emitting layer and the III-nitride layer comprising a nanopipe defect. The nanopipe terminates in the nanopipe terminating layer.

A vertical cavity surface emitting laser includes: an active layer; a first laminate for a first distributed Bragg reflector; and a first intermediate layer disposed between the active layer and the first laminate. The first intermediate layer has first and second portions. The first laminate, the first and second portions of the first intermediate layer, and the active layer are arranged along a direction of a first axis. The first laminate and the first portion of the first intermediate layer each include a first dopant. The active layer has a first-dopant concentration of less than 110.sup.16 cm.sup.3. The first portion of the first intermediate layer has a first-dopant concentration smaller than that of the first laminate. The second portion of the first intermediate layer has a first-dopant concentration smaller than that of the first portion of the first intermediate layer.

Embodiments of the invention include a III-nitride light emitting layer disposed between an n-type region and a p-type region, a III-nitride layer including a nanopipe defect, and a nanopipe terminating layer disposed between the III-nitride light emitting layer and the III-nitride layer comprising a nanopipe defect. The nanopipe terminates in the nanopipe terminating layer.

A semiconductor laser device with a quantum-dot structure allowing for improvement of its high-temperature operation characteristics is provided. The semiconductor laser device has an active-layer structure including one or more active layers. Each active layer has a quantum-dot structure. The quantum-dot structure includes: an island-shaped crystal; a lateral potential barrier layer that at least partially embeds the perimeter of the island-shaped crystal; and an upper crystal layer that covers both an upper end part of the island-shaped crystal and the lateral potential barrier layer. A first bandgap of the lateral potential barrier layer is larger than a second bandgap of the upper crystal layer.

A vertical external cavity surface emitting laser (VECSEL) structure includes a heterostructure and first and second reflectors. The heterostructure comprises an active region having one or more quantum well structures configured to emit radiation at a wavelength, .sub.lase, in response to pumping by an electron beam. One or more layers of the heterostructure may be doped. The active region is disposed between the first reflector and the second reflector and is spaced apart from the first reflector by an external cavity. An electron beam source is configured to generate the electron beam directed toward the active region. At least one electrical contact is electrically coupled to the heterostructure and is configured to provide a current path between the heterostructure and ground.

Provided is a laser device according to an embodiment of the inventive concept. The laser device includes: a semiconductor substrate; a germanium single crystal layer on the semiconductor substrate; and a pumping light source disposed on the germanium single crystal layer and configured to emit light toward the germanium single crystal layer, wherein the germanium single crystal layer receives the light to thereby output laser.