Abstract: A modulator-integrated semiconductor laser (100) includes a semiconductor laser (101), an electro-absorption modulator (102), and an optical attenuator (103) that are monolithically integrated. The electro-absorption modulator (102) and the optical attenuator (103) are connected in series in a stage succeeding the semiconductor laser (101). A control unit (44) controls the DC bias voltage to be applied to the optical attenuator (103) to increase as temperature of the modulator-integrated semiconductor laser (100) rises.

Abstract: A semiconductor laser device includes a laser section and a modulator section. The laser section has: a first mesa stripe which is formed on a semiconductor substrate; semi-insulative burying layers which are placed to abut on both side surfaces of the first mesa stripe and are formed on the semiconductor substrate; n-type burying layers formed on respective surfaces of the semi-insulative burying layers; and a p-type cladding layer which covers surfaces of the n-type burying layers and the first mesa stripe. The modulator section has: a second mesa stripe which is formed on the semiconductor substrate; semi-insulative burying layers which are placed to abut on both side surfaces of the second mesa stripe and are formed on the semiconductor substrate; and a p-type cladding layer which covers surfaces of the semi-insulative burying layers and the second mesa stripe.

Abstract: Provided is a semiconductor laser device in which a distributed feedback laser part and an electro-absorption modulator part are formed on the same semiconductor substrate, and laser light emitted from the laser part is emitted from an emission end face of the modulator part. The laser part includes a first diffraction grating formed to extend in a direction of an optical axis of the laser light and the modulator part partially including a second diffraction grating formed to extend in the direction of the optical axis of the laser. A non-diffraction grating region in which a diffraction grating is not formed is interposed between the second diffraction grating of the modulator part and an emission end face of the laser part from which the laser light is emitted to the modulator part.

Abstract: An optical transmission device includes a semiconductor laser chip in which a semiconductor laser array having a plurality of distributed feedback semiconductor lasers formed on a first semiconductor substrate is formed, a semiconductor waveguide chip in which a semiconductor modulator array formed on a second semiconductor substrate and having the same number of semiconductor modulators as the semiconductor lasers is formed. In the optical transmission device, a waveguide and a waveguide are butt-joined such that a distance between an end face of the waveguide on a side to the semiconductor modulator array in each of the semiconductor lasers of the semiconductor laser array and an end face of the waveguide on a side to the semiconductor laser array in each of the semiconductor modulators of the semiconductor modulator array is 10 ?m or less.

Abstract: An optical transmission device includes a semiconductor laser chip in which a semiconductor laser array having a plurality of distributed feedback semiconductor lasers formed on a first semiconductor substrate is formed, a semiconductor waveguide chip in which a semiconductor modulator array formed on a second semiconductor substrate and having the same number of semiconductor modulators as the semiconductor lasers is formed. In the optical transmission device, a waveguide and a waveguide are butt-joined such that a distance between an end face of the waveguide on a side to the semiconductor modulator array in each of the semiconductor lasers of the semiconductor laser array and an end face of the waveguide on a side to the semiconductor laser array in each of the semiconductor modulators of the semiconductor modulator array is 10 ?m or less.

Abstract: A semiconductor laser device includes a laser section and a modulator section. The laser section has: a first mesa stripe which is formed on a semiconductor substrate; semi-insulative burying layers which are placed to abut on both side surfaces of the first mesa stripe and are formed on the semiconductor substrate; n-type burying layers formed on respective surfaces of the semi-insulative burying layers; and a p-type cladding layer which covers surfaces of the n-type burying layers and the first mesa stripe. The modulator section has: a second mesa stripe which is formed on the semiconductor substrate; semi-insulative burying layers which are placed to abut on both side surfaces of the second mesa stripe and are formed on the semiconductor substrate; and a p-type cladding layer which covers surfaces of the semi-insulative burying layers and the second mesa stripe.

Abstract: A semiconductor optical element and an optical module in which extinction ratio variation among integrated optical modulation elements is reduced. An optical module has a wavelength multiplexer that multiplexes light respectively emerging from electric-field-absorption modulator (EAM) portions of integrated optical modulation elements, and that outputs the multiplexed light. The integrated optical modulation element has a signal input terminal, a laser element portion, and an EAM portion. Each of the integrated optical modulation elements has a difference between an oscillation wavelength and a barrier layer bandgap wavelength, represented as an LDBG wavelength difference. Variation of the LDBG wavelength differences is limited within a range of ±1 nm.

Abstract: An integrated optical modulator and laser device includes a laser section, a modulator section for modulating the intensity of a laser beam produced by the laser section, and a separation section located between the laser section and the modulator section. The laser section includes a first anode electrode and a first cathode electrode. The modulator section includes a second anode electrode and a second cathode electrode. A lower cladding layer is integral to the laser section, the modulator section, and the separation section and the width of the lower cladding layer is narrowest in the separation section.

Abstract: A semiconductor optical element and an optical module in which extinction ratio variation among integrated optical modulation elements is reduced. An optical module has a wavelength multiplexer that multiplexes light respectively emerging from electric-field-absorption modulator (EAM) portions of integrated optical modulation elements, and that outputs the multiplexed light. The integrated optical modulation element has a signal input terminal, a laser element portion, and an EAM portion. Each of the integrated optical modulation elements has a difference between an oscillation wavelength and a barrier layer bandgap wavelength, represented as an LDBG wavelength difference. Variation of the LDBG wavelength differences is limited within a range of ±1 nm.

Abstract: An electro-absorption modulator includes: a semiconductor substrate; and an n-type InP cladding layer, an AlGaInAs light absorbing layer, an InGaAsP optical waveguide layer, and a p-type InP cladding layer, which are sequentially laminated on the semiconductor substrate. The InGaAsP optical waveguide layer includes a plurality of InGaAsP layers with different constitutions. The energy barrier between valence band edges of the InGaAsP layers is smaller than the energy barrier when the InGaAsP optical waveguide layer includes only one InGaAsP layer.

Abstract: An integrated optical modulator and laser device includes a laser section, a modulator section for modulating the intensity of a laser beam produced by the laser section, and a separation section located between the laser section and the modulator section. The laser section includes a first anode electrode and a first cathode electrode. The modulator section includes a second anode electrode and a second cathode electrode. A lower cladding layer is integral to the laser section, the modulator section, and the separation section and the width of the lower cladding layer is narrowest in the separation section.

Abstract: A semiconductor optical element having a mesa structure formed by wet etching, includes a mesa structure having a ridge-type mesa structure or a high-mesa-type mesa structure, the mesa structure being disposed on a semiconductor substrate, and an extended mesa on the semiconductor substrate, the extended mesa being connected to a corner of the mesa structure and being the same material as the mesa structure.

Abstract: An electro-absorption modulator includes: a semiconductor substrate; and an n-type InP cladding layer, an AlGaInAs light absorbing layer, an InGaAsP optical waveguide layer, and a p-type InP cladding layer, which are sequentially laminated on the semiconductor substrate. The InGaAsP optical waveguide layer includes a plurality of InGaAsP layers with different constitutions. The energy barrier between valence band edges of the InGaAsP layers is smaller than the energy barrier when the InGaAsP optical waveguide layer includes only one InGaAsP layer.

Abstract: An optical modulator includes a modulation region for modulating light, and a passive region adjacent the modulation region. The modulation region and the passive region include, in common, a semiconductor substrate, an n-type cladding layer on the semiconductor substrate, a core layer on the n-type cladding layer, and a p-type cladding layer on the core layer. The modulation region further includes a contact layer on the p-type cladding layer, and a P-side electrode on the contact layer. The passive region further includes an undoped cladding layer between the core layer and the p-type cladding layer.

Abstract: A semiconductor laser (a first semiconductor optical device) and an optical modulator (a second semiconductor optical device) are integrated on the same n-type InP substrate. The semiconductor laser butt-joined to the optical modulator. Each of the semiconductor laser and the optical modulator has a Be-doped p-type InGaAs contact layer. The p-type InGaAs contact layers have a Be-doping concentration of 7×1018 cm?3 or more, and a thickness of 300 nm or less.

Abstract: A semiconductor optical element having a mesa structure formed by wet etching, includes a mesa structure having a ridge-type mesa structure or a high-mesa-type mesa structure, the mesa structure being disposed on a semiconductor substrate, and an extended mesa on the semiconductor substrate, the extended mesa being connected to a corner of the mesa structure and being the same material as the mesa structure.

Abstract: An optical waveguide has a semiconductor laser section, an intermediate section, and an optical modulator section on a surface of a substrate. The distance of a surface extending outwardly from and transverse to both sides of a mesa stripe in the semiconductor laser section from the surface of the substrate is larger than the distance of a surface extending outwardly from and transverse to both sides of the mesa stripe in the optical modulator section from the surface of the substrate. The distance of a surface extending outwardly from and transverse to both sides of the mesa stripe in the intermediate section from the surface of the substrate decreases from the semiconductor laser section toward the optical modulator section.

Abstract: A semiconductor laser (a first semiconductor optical device) and an optical modulator (a second semiconductor optical device) are integrated on the same n-type InP substrate. The semiconductor laser butt-joined to the optical modulator. Each of the semiconductor laser and the optical modulator has a Be-doped p-type InGaAs contact layer. The p-type InGaAs contact layers have a Be-doping concentration of 7×1018 cm?3 or more, and a thickness of 300 nm or less.

Abstract: An optical waveguide has a semiconductor laser section, an intermediate section, and an optical modulator section on a surface of a substrate. The distance of a surface extending outwardly from and transverse to both sides of a mesa stripe in the semiconductor laser section from the surface of the substrate is larger than the distance of a surface extending outwardly from and transverse to both sides of the mesa stripe in the optical modulator section from the surface of the substrate. The distance of a surface extending outwardly from and transverse to both sides of the mesa stripe in the intermediate section from the surface of the substrate decreases from the semiconductor laser section toward the optical modulator section.

Abstract: A semiconductor laser has a structure in which the following layers are stacked on one another over an n-type substrate: a buffer layer, a diffraction grating layer, a diffraction grating burying layer, a light confining layer, a multiple quantum well active layer, a light confining layer, and a cladding layer. In this structure, the distance D between the center of the active layer and the interface between the n-type substrate and the buffer layer is set to a value longer than the 1/e2-beam spot radius a of the laser light.