Abstract: An n-type GaAs buffer layer 702, an n-type AlGaInP cladding layer 703, a multiple quantum well active layer 704 made of AlGaInP and GaInP, a first p-type AlGaInP cladding layer 705a, an optical guide layer 707, a second p-type cladding layer 705b, a p-type GaInP saturable absorption layer 706, and a third p-type AlGaInP cladding layer 707 are sequentially formed on an n-type GaAs substrate 701. In this structure, the volume of the saturable absorption layer is reduced, and the optical guide layer is provided. As the volume of the saturable absorption layer becomes smaller, the more easily the carrier density can be increased, the more easily the saturated state can be attained, and the more remarkable the saturable absorption effect becomes. Thus, a semiconductor laser having stable self-oscillation characteristics and, as a result, having a low relative noise intensity is realized.

Abstract: A semiconductor substrate comprises a semiconductor layer comprising a group III nitride as a main component. A scattering portion for scattering an incident beam of light incident on one plane of the semiconductor layer is provided on another plane or inside of the semiconductor layer.

Abstract: The semiconductor laser of this invention includes an active layer formed in a c-axis direction, wherein the active layer is made of a hexagonal-system compound semiconductor, and anisotropic strain is generated in a c plane of the active layer.

Abstract: An n-type GaAs buffer layer 702, an n-type AlGaInP cladding layer 703, a multiple quantum well active layer 704 made of AlGaInP and GaInP, a first p-type AlGaInP cladding layer 705a, an optical guide layer 707, a second p-type cladding layer 705b, a p-type GaInP saturable absorption layer 706, and a third p-type AlGaInP cladding layer 707 are sequentially formed on an n-type GaAs substrate 701. In this structure, the volume of the saturable absorption layer is reduced, and the optical guide layer is provided. As the volume of the saturable absorption layer becomes smaller, the more easily the carrier density can be increased, the more easily the saturated state can be attained, and the more remarkable the saturable absorption effect becomes. Thus, a semiconductor laser having stable self-oscillation characteristics and, as a result, having a low relative noise intensity is realized.

Abstract: In a semiconductor laser including an active layer and a buried layer for absorbing laser light emitted from the active layer, an oscillation wavelength of the laser light is in a 650 nm band, an oscillation mode is a single transverse mode, and a peak of a light intensity distribution of the laser light is placed on the side opposite to the buried layer with respect to the center of the active layer.

Abstract: A semiconductor laser device of the present invention includes a substrate 201 made of n-type GaAs, an active layer 204, and a pair of cladding layers sandwiching the active layer 204. The device further includes a spacer layer 205 adjacent to the active layer 204 and a highly doped saturable absorbing layer 206. The carrier life time is shortened by doping the saturable absorbing layer 206 in a high concentration, whereby stable self-sustained pulsation can be obtained. As a result, a semiconductor laser device can be obtained, which has a low relative noise intensity in a wide range of temperatures.

Abstract: A semiconductor laser device of the present invention includes a substrate 201 made of n-type GaAs, an active layer 204, and a pair of cladding layers sandwiching the active layer 204. The device further includes a spacer layer 205 adjacent to the active layer 204 and a highly doped saturable absorbing layer 206. The carrier life time is shortened by doping the saturable absorbing layer 206 in a high concentration, whereby stable self-sustained pulsation can be obtained. As a result, a semiconductor laser device can be obtained, which has a low relative noise intensity in a wide range of temperatures.

Abstract: A semiconductor laser device of the present invention includes a substrate 201 made of n-type GaAs, an active layer 204, and a pair of cladding layers sandwiching the active layer 204. The device further includes a spacer layer 205 adjacent to the active layer 204 and a highly doped saturable absorbing layer 206. The carrier life time is shortened by doping the saturable absorbing layer 206 in a high concentration, whereby stable self-sustained pulsation can be obtained. As a result, a semiconductor laser device can be obtained, which has a low relative noise intensity in a wide range of temperatures.

Abstract: The semiconductor laser of this invention includes an active layer formed in a c-axis direction, wherein the active layer is made of a hexagonal-system compound semiconductor, and anisotropic strain is generated in a c plane of the active layer.

Abstract: A lateral mode control type of semiconductor laser has a high-yield structure having a long life and improved oscillation wavelength reproducibility. A diffusion limit layer formed of an undoped Ga.sub.0.5 In.sub.0.5 P layer and an undoped (Al.sub.0.6 Ga.sub.0.4).sub.0.5 In.sub.0.5 P layer is provided between a p-(Al.sub.0.6 Ga.sub.0.4).sub.0.5 In.sub.0.5 P clad layer and an undoped Ga.sub.0.5 In.sub.0.5 P active layer. The diffusion limit layer has a diffusion coefficient smaller than that of the clad layer. Impurity Zn diffused from the p-(Al.sub.0.6 Ga.sub.0.4).sub.0.5 In.sub.0.5 P clad layer during crystal growth or working is trapped in the undoped Ga.sub.0.5 In.sub.0.5 P layer almost entirely. A part of the impurity Zn diffuses in the undoped (Al.sub.0.6 Ga.sub.0.4).sub.0.5 In.sub.0.5 P layer thereunder but does not reach the undoped Ga.sub.0.5 In.sub.0.5 P active layer.

Abstract: A method of fabricating a semiconductor laser includes successively forming on a semiconductor substrate by crystal growth an active waveguide comprised of a compound semiconductor comprising a Group V element phosphorus, a thin-film layer comprised of a first-conductivity type compound semiconductor comprising a Group V element arsenic and a current blocking layer comprised of a second-conductivity type compound semiconductor comprising a Group V element arsenic. A mask is formed for selectively etching the current blocking layer in the form of a stripe. A buffer-etching step is formed on both the current blocking layer and the mask to expose a surface of the current blocking layer and the thin-film layer, the surface including a Group V element arsenic. An outer cladding layer comprising a first-conductivity type compound semiconductor having a Group V element arsenic is formed on the current blocking layer and the thin-film layer in an atmosphere having a Group V element arsenic.

Abstract: A semiconductor laser comprising an active waveguide formed of a compound semiconductor comprising a Group V element phosphorous, comprised of an active layer and two cladding layers that hold the active layer between them, and a current confinement structure formed on the active waveguide by the use of a compound semiconductor comprising Group V element arsenic. This semiconductor laser can achieve a small astigmatism, a low threshold current and a low operation current. Also disclosed is a method of fabricating a semiconductor laser having characteristic features that the crystal growth may be carried out only twice, the movement of the impurities in crystals does not easily occur, a regrowth interface with a very little defect can be readily obtained, and the structure wherein the outer cladding layer has a smaller width at its portion nearer to the active waveguide can be naturally formed.