A semiconductor optical device includes a substrate of a first conductivity type; an optical confinement layer of the first conductivity type, which is arranged above the substrate of the first conductivity type; a multi quantum well layer, which is arranged above the optical confinement layer of the first conductivity type, and comprises a plurality of well layers and a plurality of barrier layers; an optical confinement layer of a second conductivity type, which is arranged on the multi quantum well layer; and a PL stabilization layer, which is arranged between the substrate of the first conductivity type and the multi quantum well layer. The PL stabilization layer having a thickness that is half a thickness of the multi quantum well layer or more, and having a composition wavelength that is shorter than a composition wavelength of the plurality of well layers of the multi quantum well layer.

A semiconductor optical device includes a substrate having an optical waveguide, a gain section formed of a compound semiconductor having an optical gain and bonded to an upper surface of the substrate, the gain section having a first mesa, and a first wiring line electrically connected to the gain section. The first mesa of the gain section is optically coupled to the optical waveguide. The substrate includes a first layer, a second layer, and a third layer. The first layer has a higher thermal conductivity than the second layer. The second layer is stacked on the first layer. The third layer is stacked on the second layer. A recess provided in the substrate extends through the third layer to the second layer in the thickness direction. The first wiring line extends from the first mesa of the gain section to the recess.

A strained quantum well structure of the present disclosure is a type I strained quantum well structure grown by using an InP crystal as a substrate and including a luminescence wavelength of 1.9 μm or longer and 2.5 μm or shorter, in which a well layer is an InGaAs, InAs, or InGaAsSb crystal including a compression strain, a barrier layer is an InGaAsSb crystal including a tensile strain, and a band discontinuity in a conduction band is 100 meV or greater.

A laser including a grating configured to reduce lasing threshold for a selected vertically confined mode as compared to other vertically confined modes.

An optical integrated light source includes a plurality of topological ring resonators. Each of the topological ring resonators is defined by an interface between two distinct periodic structures having different topological invariants such that a one-way edge mode may be excited along the interface. A magnetic material is arranged to interact with the plurality of topological ring resonators such that the optical integrated light source is structured and configured to generate plural beams each carrying large orbital angular momentum.

A semiconductor optical device includes a substrate formed of silicon and having a first optical waveguide and a semiconductor element formed of a III-V compound semiconductor and having a second optical waveguide, the semiconductor element being bonded to an upper surface of the substrate. The first optical waveguide and the second optical waveguide form a directional coupler.

A laser including a grating configured to reduce lasing threshold for a selected vertically confined mode as compared to other vertically confined modes.

A semiconductor laser device includes: a main body including a first layer having n-type conductivity, a second layer having p-type conductivity, and an active layer interposed between the first layer and the second layer, the first layer, the second layer, and the active layer being laminated in a lamination direction; a front-side mirror formed on a front facet of the main body, the front facet being parallel to the lamination direction; and a rear-side mirror formed on a rear facet of the main body, the rear facet facing the front facet in an optical waveguide direction that crosses the lamination direction and the front facet. The first layer includes an electric field control layer having a shorter composition wavelength than an emission wavelength of the active layer. The second layer includes an optical guide layer having a shorter composition wavelength than the emission wavelength of the active layer.

An insulating film (10) having an opening (11) is formed on a contact layer (7). A shape stabilization layer (8) having an inclined surface (9) is formed on the contact layer (7) in a peripheral portion of the opening (11). An underlying metal (12) covers an upper surface of the contact layer (7) exposed through the opening (11) and the inclined surface (9). A plating (13) is formed on the underlying metal (12).

A method for tuning an emission wavelength of a laser device, including: acquiring a drive condition of a wavelength tunable laser diode to make the wavelength tunable laser diode oscillate at a wavelength from a memory; driving a first thermo-cooler and a first heater based on the drive condition of the wavelength tunable laser diode; determining whether respective control values of the first thermo-cooler and the first heater are reached within a first range of target values; and driving a gain region after the control values have been reached within the first range.