A semiconductor laser device having a diffraction grating is disclosed. The semiconductor laser device comprises a first diffraction grating provided on a substrate, a second diffraction grating continuous to one end of the first diffraction grating along an optical waveguide direction, and an active layer provided above the first diffraction grating. The second diffraction grating has a pitch 1.05 times or greater, or 0.95 times or smaller of the pitch of the first diffraction grating.

A semiconductor laser includes a ridge structure formed on an n-type semiconductor substrate, and a buried layer buried so as to cover both sides of the ridge structure opposed to each other in a direction perpendicular to an extending direction of the ridge structure. The ridge structure includes an n-type cladding layer, an active layer, and a p-type cladding layer formed sequentially from a side of the n-type semiconductor substrate. The buried layer includes a p-type semiconductor layer in contact with both side surfaces of the p-type cladding layer and the active layer in the ridge structure, and a semi-insulating layer, and the p-type semiconductor layer is not in contact with the n-type cladding layer of the ridge structure.

In a luminescent diode and a method for manufacturing the same, a planar buried heterostructure (PBH) and a ridge waveguide structure are combined, so that the luminescent diode can be operated to generate a high output of 100 mW or more at low current. Further, it is possible to reduce electro-optic loss. In addition, the luminescent diode is applied to a wavelength tunable external cavity laser, so that it is possible to provide an external cavity laser having excellent output characteristics.

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; a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer; and 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.

A semiconductor optical device in which a light emitting region that emits light and a reflecting region that reflects the light to the light emitting region side are integrated includes a core layer that is provided in the light emitting region, and a waveguide layer that is provided in the reflecting region, that is optically coupled to the core layer, and that has a band gap that is larger than energy of the light. The reflecting region has a first thyristor that overlaps the waveguide layer in a direction that intersects a propagation direction of the light.

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; a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer; and 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.

An apparatus comprising a laser comprising an active layer and configured to emit an optical signal, wherein a temperature change of the laser causes the optical signal to shift in wavelength, and a heater thermally coupled to the active layer and configured to reduce a wavelength shift of the optical signal by applying heat to the active layer.

In a luminescent diode and a method for manufacturing the same, a planar buried heterostructure (PBH) and a ridge waveguide structure are combined, so that the luminescent diode can be operated to generate a high output of 100 mW or more at low current. Further, it is possible to reduce electro-optic loss. In addition, the luminescent diode is applied to a wavelength tunable external cavity laser, so that it is possible to provide an external cavity laser having excellent output characteristics.

An upper cladding layer includes a first low carrier concentration layer having a lower carrier concentration than the p-type cladding layer and a first Fe-doped semiconductor layer formed on the first low carrier concentration layer. The leakage current suppression layer includes a second Fe-doped semiconductor layer disposed on a side of the p-type semiconductor layer. The first low carrier concentration layer has a side wall part that is in contact with a side face of the p-type cladding layer. The first Fe-doped semiconductor layer is disposed on a side of the p-type cladding layer via the side wall part of the first low carrier concentration layer and is not in contact with the p-type cladding layer.

An apparatus comprising a burst-mode laser comprising an active layer and configured to emit an optical signal during a burst period, wherein a temperature change of the burst-mode laser causes the optical signal to shift in wavelength, and a heater thermally coupled to the active layer and configured to reduce a wavelength shift of the optical signal during the burst period by applying heat to the active layer based on timing of the burst period.