Abstract: A laser device includes a double hetero-structure element constructed by depositing a p-type cladding layer, a quantum well active layer, an n-type thin first cladding layer and an n-type thick second cladding layer sequentially. A ridge-waveguide is shaped between two trenches formed in the second cladding layer. The first cladding layer serves as an etching stopper while etching the second cladding layer to form the two trenches. The trenches reach to or reach in vicinity to the surface of the first cladding layer. High-resistance regions may be formed in portions of the first cladding layer directly underneath the trenches. The thin first cladding layer, suppresses leakage current and improves the temperature characteristics and the operating speed characteristics of the laser device.

Abstract: A surface-emitting semiconductor laser device, having a mesa which emits a laser beam from a top surface of the mesa. The laser device includes an active layer, first and second multi-layer reflecting films, first and second electrode, and a contact layer. The first and second multi-layer reflecting films sandwich the active layer in a direction perpendicular to the surface of the active layer. The first and second electrodes sandwich the active layer in the direction perpendicular to the surface of the active layer. The contact layer extends from a side surface of the second multi-layer film to a top surface of the second multi-layer reflecting film such that the second electrode is connected to the first multi-layer film through the contact layer. The mesa includes the active layer, the second multi-layer reflecting film, and an aperture is provided on the top surface of the second multi-layer reflecting film.

Abstract: A ridge waveguide distributed feedback laser includes a p-type InGaAsP grating layer having a p-type carrier density ranging from 1.5×1018 cm−3 to 4.0×10−3 cm−3 and preferably from 2.0×1018 cm−3 to 3.0×1018 cm−3. In combination with such raised levels of p-type carrier density in the InGaAsP grating layer, the p-type carrier density may also be enhanced both in a p-type InP layer between the grating layer and a contact layer, and in another p-type InP layer between the grating layer and a quantum well active layer, the density ranging from 1.5×1018 cm−3 to 4.0×1018 cm−3 and preferably from 2.0×1018 cm−3 to 3.0×1018 cm−3.

Abstract: A distributed feedback laser device includes a semiconductor base having a ridge waveguide structure projecting from its principal plane. The ridge waveguide structure extends with a predetermined width from one edge of the semiconductor base to an opposite edge. A diffraction grating layer is confined within the ridge structure. The ridge waveguide structure is formed by etching using an SiO2 film and a resist film as masks so that the diffraction grating layer is produced with substantially the same width as, or a less width than, the width of the ridge waveguide structure. A &lgr;/4 shift diffraction grating or a chirped diffraction grating is preferably employed.

Abstract: On a laminate containing a p-InGaAsP layer, one of layers including a diffraction grating layer, an SiO2 insulating film pattern that has first rectangular openings, each opening having a long side orthogonal with the direction of the optical wave guide, periodically arranged at intervals in the direction of the optical wave guide is formed. An SiN insulating film pattern having a second opening with a strip shape having a width narrower than the long side of the first opening, extending in the direction of the optical wave guide, is formed on the SiO2 insulating film pattern. The laminate containing the p-InGaAsP layer is dry-etched using the SiO2 insulating film pattern and the SiN insulating film pattern as masks, and methane and a hydrogen plasma as the etching media.

Abstract: A ridge waveguide type distributed feedback laser comprises a p-type InGaAsP grating layer having a p-type carrier density ranging from 1.5×1018 cm−3 to 4.0×1018 cm−3 and preferably from 2.0×1018 cm−3 to 3.0×1018 cm−3. In combination with such raised levels of p-type carrier density in the InGaAsP grating layer, the p-type carrier density may also be enhanced both in a p-type InP layer between the grating layer and a contact layer, and in another p-type InP layer between the grating layer and a quantum well active layer, the density ranging from 1.5×1018 cm−3 to 4.0×1018 cm−3 and preferably from 2.0×1018 cm−3 to 3.0×1018 cm−3.

Abstract: A laser device includes a double hetero-structure element constructed by depositing a p-type cladding layer, a quantum well active layer, an n-type thin first cladding layer and an n-type thick second cladding layer sequentially. A ridge-waveguide is shaped between two trenches formed in the second cladding layer. The first cladding layer serves as an etching stopper while etching the second cladding layer to form the two trenches. The trenches reach to or reach in vicinity to the surface of the first cladding layer. High-resistance regions may be formed in portions of the first cladding layer directly underneath the trenches. The thin first cladding layer, suppresses leakage current and improves the temperature characteristics and the operating speed characteristics of the laser device.

Abstract: On a laminate containing a p-InGaAsP layer 39, one of layers composing the diffraction grating layer, an SiO2 insulating film pattern 41a that has a plurality of first rectangular openings 41b each having a long side orthogonal with the direction of the optical wave guide, periodically arranged at intervals in the direction of the optical wave guide is formed.

Abstract: A ridge waveguide semiconductor laser that is excellent in optical output characteristic and high-frequency characteristic is provided. A p-type InP cladding layer having a ridge shape is formed over a p-type AlInAs cladding layer via a p-type InP layer and a p-type GaInAsP etching stopper layer, thereby suppressing the increase in the series resistance due to discontinuous band structure between an etching stopper layer and the AlGaInAs cladding layer and reducing the threshold current of the laser. Also the InP cladding layer is formed in a ridge shape with the portion near the base thereof being splayed like a skirt, thereby keeping the p-type metal electrode from the light emitting region and suppressing the absorption loss of light due to the p-type metal electrode.

Abstract: An electrode for a semiconductor device includes a gold-containing thin film and a gold-containing plated film on the thin film. The plated film covers the entire thin film. No open surface is present between the thin gold film and the gold plating so no excessive current concentration occurs in any area.

Abstract: An integrated semiconductor laser-modulator device less affected by a fluctuating electric field due to modulating signals applied to the modulator has improved frequency characteristics. The integrated semiconductor laser-modulator includes an active layer, a beam waveguide layer having a bulk structure with a bandgap energy larger than that of the active layer but smaller than that of a laser beam absorption layer having a bulk structure, wherein waveguides of the laser and modulator are connected and aligned, and a cladding layer including a diffraction grating is disposed on top of or beneath the waveguides.

Abstract: An electrode for power supply of a semiconductor device is disclosed. The electrode has a gold-containing thin film and a gold-containing plating formed on the thin film. The plating covers the entire thin film.

Abstract: A distributed feedback laser device is disclosed which comprises a semiconductor base having a ridge waveguide structure projecting from its principal plane, the ridge waveguide structure extending with a predetermined width from one edge of the semiconductor base to its opposite edge, wherein a diffraction grating layer is formed confined within the ridge structure. The ridge waveguide structure is formed by an etching process using an SiO2 film and a resist film as masks so that the diffraction grating layer is produced with substantially the same width as, or a less width than, the width of the ridge waveguide structure. A &lgr;/4 wavelength shift diffraction grating or a chirped diffraction grating may preferably be incorporated.

Abstract: A semiconductor laser diode includes a mesa having a width on a semiconductor substrate and aligned with a direction of resonance, a current blocking layer formed by selective growth on both sides of the mesa and having a first embedded layer and a second embedded layer covering the first embedded layer.

Abstract: A composite optical device having a high efficiency of coupling a laser diode and an optical device and a method of producing the composite optical device. The composite optical device connects a laser diode with a first mesa including an active layer on a (001) plane of a compound semiconductor substrate via a first cladding layer and an optical device provided with a second mesa including an optical waveguide layer formed on the (001) plane via a second cladding layer, wherein one end of the active layer and one end of the optical waveguide layer oppose each other at a distance smaller than the thicknesses of the first and second cladding layers. At least the second cladding layer is grown in an ambient supplemented with HCl to produce a planar surface.

Abstract: A semiconductor optical device includes a first semiconductor layer, and a diffraction grating disposed on the first semiconductor layer. The diffraction grating includes portions of a superlattice layer grown on the first semiconductor layer and including alternatingly arranged second semiconductor layers of a semiconductor material in which mass transport hardly occurs during growth of other semiconductor layers and third semiconductor layers of a semiconductor material different from the material of the second semiconductor layers. The device includes a fourth semiconductor layer burying the diffraction grating. In this structure, since the second semiconductor layers are included in the diffraction grating, the shape of the diffraction grating is maintained during the vapor phase deposition of the fourth semiconductor layer. Therefore, the thickness, amplitude, and pitch of the diffraction grating that determine the optical coupling constant are controlled with high precision.

Abstract: A light absorption modulator includes a semiconductor substrate of a first conductivity type; a first cladding layer of the first conductivity type disposed on the substrate; an optical waveguide disposed on the first cladding layer and including a multiple quantum well optical waveguide layer through which light travels and first and second light confinement layers respectively disposed on opposed surfaces of the optical waveguide layer to confine light in the optical waveguide layer; and a second cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the optical waveguide, one of the first and second cladding layers being n type, the one of the first and second light confinement layers that contacts the n type cladding layer being p type, and light traveling through the optical waveguide layer being modulated by applying an electric field to the optical waveguide layer.

Abstract: A method of making a semiconductor optical device, including an integrated laser diode and optical waveguide lens with a continuous resonator extending along a resonator length direction between a pair of resonator facets, includes forming a pair of dielectric films disposed on a surface of a substrate on which a semiconductor layer of the optical waveguide is to be grown, the dielectric films having a linear symmetry about a hypothetical line extending in the resonator length direction, having edges opposing each other and parallel to the hypothetical line, and widths perpendicular to the resonator length direction that gradually narrow toward one facet from a position in the resonator length direction of the films. A mask pattern that produces a precise layer thickness profile is easily designed.

Abstract: A semiconductor device includes a substrate having a lattice constant and a stress compensation strained quantum well layer including compressively strained layers having a lattice constant larger than the lattice constant of the substrate and tensively strained layers having a lattice constant smaller than the lattice constant of the substrate which are alternatingly laminated on the substrate, wherein the average strain of the stress compensation strained quantum well layer is a positive quantity. Therefore, the critical thickness of the strained quantum well layer is increased so that the degree of freedom in designing the strained quantum well layer is increased, resulting in a semiconductor device with improved characteristics.

Abstract: A semiconductor laser device includes an active layer having a multiquantum well (MQW) structure including well layers and barrier layers, each well layer being disposed between a pair of barrier layers. In this structure, the barrier layers have respective band gap energies that gradually decrease from a largest value in a central part of the MQW structure toward interfaces of the MQW structure with other layers of the laser and the well layers have respective band gap energies that gradually increase from a smallest value in the central part of the MQW structure toward the interfaces. A semiconductor laser device that produces uniform charge carrier injection, has a high thermal electron emission efficiency, and a broad modulation bandwidth is realized.