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 quantum well active layer is doped with 0.3 to 1×10.sup.18/cm.sup.3 of n-type impurity.

A semiconductor laser device includes an N-type cladding layer, an active layer, and a P-type cladding layer. The active layer includes a well layer, a P-side first barrier layer above the well layer, and a P-side second barrier layer above the P-side first barrier layer. The P-side second barrier layer has an AI composition ratio higher than an AI composition ratio of the P-side first barrier layer. The P-side second barrier layer has band gap energy greater than band gap energy of the P-side first barrier layer. The semiconductor laser device has an end face window structure in which band gap energy of a portion of the well layer in a vicinity of an end face that emits the laser light is greater than band gap energy of a central portion of the well layer in a resonator length direction.

A laser diode apparatus has a first waveguide layer including a gain region connected in series with a second waveguide layer with a second gain region. A tunnel junction is positioned between the first and second guide layers. A single collimator is positioned in an output path of laser beams emitted from the first and second waveguide layers. The optical beam from the single collimator may be coupled into an optical fiber.

A Vertical Cavity Surface Emitting Laser VCSEL, includes an optical resonator with a first reflector, a second reflector, and an active region for laser emission arranged between the first reflector and the second reflector and remaining regions outside of the active region, and an electrical contact arrangement configured to provide an electrical drive current to electrically pump the optical resonator. The optical resonator further comprises a loss layer introducing optical and/or electrical losses to increase wavelength shift of the laser emission when varying the drive current. If the loss layer is an optical loss layer, the optical losses introduced by the loss layer are higher than the sum of the optical losses in the remaining regions. If the loss layer is an electrical loss layer, the electrical losses introduced by the loss layer are higher by a factor of at least 5 than the electrical losses in the remaining regions.

A Bragg grating includes a lower waveguide layer, a middle waveguide layer disposed on the lower waveguide layer, an upper waveguide structure disposed on the middle waveguide layer opposite to the lower waveguide layer, and a buried layer. The upper waveguide structure includes upper waveguide elements that are arranged on a surface of the middle waveguide layer, and that are spaced apart from one another by cavities. The buried layer fills the cavity. The middle waveguide layer has a refractive index lower than that of each of the lower waveguide layer and the upper waveguide elements. The lower waveguide layer has a doping type the same as that of the middle waveguide layer. A method for manufacturing the Bragg grating is also provided.

A light-emitting device includes a light emission section (Em), a separation groove (152), and a high reflectance region (Hr). The light emission section (Em) includes a stack structure (100) including an active layer (100), a first reflector (110), and a second reflector (120). The active layer (130) performs light emission by current injection. The first reflector (110) and the second reflector (120) are stacked in a first direction with the active layer (130) interposed therebetween. The separation groove (152) is provided symmetrically around the light emission section (Em) on an emission surface of light from the stack structure (100) in the first direction. The separation groove (152) is dug in the stack structure (100) in the first direction. The high resistance region (Hr) is provided in the stack structure (100) on the outer side of an outermost shape of the separation groove (152) on the emission surface. The high resistance region (Hr) has electrical resistance higher than that of the light emission section (Em).

A vertical cavity light-emitting element includes a substrate, a first multilayer film reflecting mirror, a semiconductor structure layer, an electrode, an electrode layer, and a second multilayer film reflecting mirror. The first multilayer film reflecting mirror is formed on the substrate. The semiconductor structure layer includes a nitride semiconductor. The nitride semiconductor includes a first semiconductor layer that is formed on the first multilayer film reflecting mirror and is a first conductivity type, a second semiconductor layer that is formed on the first semiconductor layer and is the first conductivity type, a light-emitting layer that is formed on the second semiconductor layer and is configured to expose a region including an outer edge of a top surface of the second semiconductor layer, and a third semiconductor layer that is formed on the light-emitting layer and is a second conductivity type opposite to the first conductivity type. The electrode is formed on the top surface of the second semiconductor layer. The electrode layer is electrically in contact with the third semiconductor layer in one region of a top surface of the third semiconductor layer. The second multilayer film reflecting mirror constitutes a resonator with the first multilayer film reflecting mirror. The second semiconductor layer has a larger resistance than the first semiconductor layer.

A light-emitting device according to an embodiment of the present disclosure includes: a semiconductor stack in which a first light reflection layer configured by an arsenic-based semiconductor layer including carbon as an impurity, an active layer, and a second light reflection layer are stacked; a first buffer layer provided on the first light reflection layer side of the semiconductor stack, having one face that faces the semiconductor stack and another face that is on an opposite side of the one face, and configured by a phosphorus-based semiconductor layer; and a second buffer layer provided at least between the first light reflection layer and the first buffer layer, and configured by an arsenic-based semiconductor layer including zinc or magnesium as an impurity.

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 vertical cavity surface emitting laser (VCSEL) has first and second electrical contacts, and an optical resonator. The optical resonator has first and second distributed Bragg reflectors (DBRs), an active layer, a distributed heterojunction bipolar phototransistor (DHBP), and an optical guide. The DHBP has a collector layer, light sensitive layer; a base layer; and an emitter layer. There is an optical coupling between the active layer and the DHBP for providing an active carrier confinement by the DHBP. The optical guide guides an optical mode within the optical resonator during operation. The optical guide is outside a current flow which can be provided by the first and second electrical contacts during operation of the VCSEL. The optical guide is outside a layer sequence between the first and second electrical contacts in the vertical direction of the VCSEL. The optical guide has an oxide aperture arranged in the second DBR.