A buried typed semiconductor optical device includes a semiconductor substrate having a pair of grooves extending in a first direction. An upper surface of a buried layer has a first region that is adjacent to a mesa stripe structure, overlaps with a corresponding one of the pair of grooves, is inclined so as to be higher in a second direction from the mesa stripe structure, and on which a passivation film is not formed. The upper surface of the buried layer has a second region that does not overlap with any of the pair of grooves, is flat, and is higher than a lower end of the first region, and on which the passivation film is formed. The upper surface of the buried layer has a connection region between the first region and the second region at a same height as the second region.

A laser chip including a plurality of stripes is disclosed, where a laser stripe can be grown with an initial optical gain profile, and its optical gain profile can be shifted by using an intermixing process. In this manner, multiple laser stripes can be formed on the same laser chip from the same epitaxial wafer, where at least one laser stripe can have an optical gain profile shifted relative to another laser stripe. For example, each laser stripe can have a shifted optical gain profile relative to its neighboring laser stripe, thereby each laser stripe can emit light with a different range of wavelengths. The laser chip can emit light across a wide range of wavelengths. Examples of the disclosure further includes different regions of a given laser stripe having different intermixing amounts.

Disclosed are a wavelength-selectable laser diode and an optical communication apparatus including the same. The wavelength-selectable laser diode includes a substrate, which includes a gain region, a tuning region spaced apart from the gain region, and a phase adjusting region between the tuning region and the gain region, a waveguide layer on the substrate, a clad layer on the waveguide layer, and gratings disposed on the substrate or the clad layer in the gain region and the tuning region.

A light modulation element according to example embodiments includes a substrate; a first lower DBR layer on the substrate including a first material layer alternately stacked with a second material layer having a different refractive index from the first material layer; a second lower DBR layer on the first lower DBR layer with a surface area less than the first lower DBR layer and including a third material layer alternately stacked with a fourth material layer having a different refractive index from the third material layer; an active layer on the second lower DBR layer, including a semiconductor material having a multi-quantum well structure and having a refractive index that varies according to an applied voltage; and an upper DBR layer on the active layer including a fifth material layer alternately stacked with a sixth material layer having a different refractive index from the fifth material layer.

According to one embodiment, an optical semiconductor element includes a substrate, a light emitting layer, and a distributed Bragg reflector. The light emitting layer includes an AlGaAs multi quantum well layer. The distributed Bragg reflector is provided between the substrate and the light emitting layer. A pair of a first layer and a second layer is periodically stacked in the distributed Bragg reflector. The first layer includes Al.sub.xGa.sub.1-xAs. The second layer includes In.sub.z(Al.sub.yGa.sub.1-y).sub.1-zP. A refractive index n.sub.1 of the first layer is higher than a refractive index n.sub.2 of the second layer. The first layer has a thickness larger than λ0/(4n.sub.1) where λ0 is a center wavelength of a band on wavelength distribution of a reflectivity of the distributed Bragg reflector. The second layer has a thickness smaller than λ0/(4n.sub.2).

It is provided a method for fabricating an electroabsorption modulated laser comprising generating a single mode laser section and an electroabsorption modulator section, comprising fabricating at least one n-doped layer of the laser section and at least one n-doped layer of the modulator section; generating an isolating section for electrically isolating at least the n-doped layer of the laser section and the n-doped layer of the modulator section from one another. Generating the isolating section comprises epitaxially growing at least one isolating layer and structuring the isolating layer before the generation of the n-doped layer of the laser section and the n-doped layer of the modulator section.

A buried typed semiconductor optical device includes a semiconductor substrate having a pair of grooves extending in a first direction. An upper surface of a buried layer has a first region that is adjacent to a mesa stripe structure, overlaps with a corresponding one of the pair of grooves, is inclined so as to be higher in a second direction from the mesa stripe structure, and on which a passivation film is not formed. The upper surface of the buried layer has a second region that does not overlap with any of the pair of grooves, is flat, and is higher than a lower end of the first region, and on which the passivation film is formed. The upper surface of the buried layer has a connection region between the first region and the second region at a same height as the second region.

According to one embodiment, an optical semiconductor element includes a substrate, a light emitting layer, and a distributed Bragg reflector. The light emitting layer includes an AlGaAs multi quantum well layer. The distributed Bragg reflector is provided between the substrate and the light emitting layer. A pair of a first layer and a second layer is periodically stacked in the distributed Bragg reflector. The first layer includes Al.sub.xGa.sub.1-xAs. The second layer includes In.sub.z(Al.sub.yGa.sub.1-y).sub.1-zP. A refractive index n.sub.1 of the first layer is higher than a refractive index n.sub.2 of the second layer. The first layer has a thickness larger than 0/(4n.sub.1) where 0 is a center wavelength of a band on wavelength distribution of a reflectivity of the distributed Bragg reflector. The second layer has a thickness smaller than 0/(4n.sub.2).

A semiconductor laser (1) emits laser light. An electro-absorption optical modulator (2) modulates the laser light. The electro-absorption optical modulator (2) includes a plurality of electro-absorption regions (2a, 2b, 2c) having different extinction characteristics, whereby the extinction ratio curve of the optical device can be controlled to have a shape with multiple steps that is suited to driving conditions.

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.