Abstract: A semiconductor laser includes a substrate made of InP, an active layer including a multiquantum well structure, which is formed in a width of 7 to 14 ?m on the substrate, and an n-type cladding layer made of InGaAsP and a p-type cladding layer made of InP, which are formed on the substrate with the active layer interposed therebetween. The semiconductor laser oscillates only in the fundamental lateral mode, and light emitted from an exit facet can be optically coupled with an external single mode optical fiber.

Abstract: A semiconductor laser includes a substrate made of InP, an active layer including a multiquantum well structure, which is formed in a width of 7 to 14 ?m on the substrate, and an n-type cladding layer made of InGaAsP and a p-type cladding layer made of InP, which are formed on the substrate with the active layer interposed therebetween. The semiconductor laser oscillates only in the fundamental lateral mode, and light emitted from an exit facet can be optically coupled with an external single mode optical fiber.

Abstract: A tunable wavelength semiconductor laser includes an n-type semiconductor substrate, an active layer which is disposed above the n-type semiconductor substrate and which generates light, a p-type cladding layer disposed above the active layer, and wavelength selecting section for causing to selectively oscillate only a specific wavelength from the light generated in the active layer. The tunable wavelength semiconductor layer capable of oscillating at the specific wavelength can be performed by injecting current into the active layer, and the specific wavelength can be varied by changing the magnitude of the current. A device length showing a length in a propagation direction of the light generated in the active layer is about 200 ?m to 500 ?m, and a width of the active layer orthogonal to the propagation direction of the light generated in the active layer, and showing a length in a direction parallel to the n-type semiconductor substrate is about 1 ?m to 2 ?m.

Abstract: An optical semiconductor device (1) has a semiconductor substrate (2) made of InP, an active layer (7) which is formed in parallel with a top surface (2a) of the semiconductor substrate (2) above the semiconductor substrate (2), an n-type first cladding layer (6) made of InGaAsP which is formed under the active layer (7), a p-type second cladding layer (8) made of InP which is formed under the active layer (7), and window regions (4a, 4b) which are formed at least one light-emitting facet of both light-emitting facets of the active layer (7). The window regions are formed between device facets (1a, 1b) from the light-emitting facet.

Abstract: First and second diffraction grating layers are provided above a semiconductor substrate, and are spaced from each other in an output direction of a beam with a flat connecting layer sandwiched therebetween. An active layer is disposed above or below the first and second diffraction grating layers and the connecting layer. A cladding layer is disposed above the active layer or above the first and second diffraction grating layers and the connecting layer. A diffraction grating including the first and second diffraction grating layers has a plurality of slits penetrating from an upper surface to a lower surface that are perpendicular to the output direction of the beam. The connecting layer is formed from two layers grown epitaxially in a direction perpendicular to the output direction of the beam. One of the two layers is formed of the same material as the first and second diffraction grating layers.

Abstract: The semiconductor light emitting device includes a semiconductor substrate formed from InP, an active layer, an n-type cladding layer formed from InGaAsP, and a p-type cladding layer formed from InP. The active layer is formed at the upper side of the semiconductor substrate. The n-type cladding layer and the p-type cladding layer are formed so as to hold the active layer therebetween. The semiconductor light emitting device is, given that, a refractive index of the n-type cladding layer is na, and a refractive index of the p-type cladding layer is nb, set so as to be the relationship of na>nb in which the refractive index na of the n-type cladding layer is higher than the refractive index nb of the p-type cladding layer, and due to the distribution of light generated by the active layer being deflected to the n-type cladding layer side, optical loss by intervalence band light absorption at the p-type cladding layer is suppressed, and high-power light output can be obtained.

Abstract: The semiconductor light emitting device includes a semiconductor substrate formed from InP, an active layer, an n-type cladding layer formed from InGaAsP, and a p-type cladding layer formed from InP. The active layer is formed at the upper side of the semiconductor substrate. The n-type cladding layer and the p-type cladding layer are formed so as to hold the active layer therebetween. The semiconductor light emitting device is, given that, a refractive index of the n-type cladding layer is na, and a refractive index of the p-type cladding layer is nb, set so as to be the relationship of na>nb in which the refractive index na of the n-type cladding layer is higher than the refractive index nb of the p-type cladding layer, and due to the distribution of light generated by the active layer being deflected to the n-type cladding layer side, optical loss by intervalence band light absorption at the p-type cladding layer is suppressed, and high-power light output can be obtained.

Abstract: An n-type semiconductor substrate has a (100) crystal plane as an upper surface. A mesa stripe portion has a trapezoidal shape including an n-type first clad layer, an active layer and a p-type second clad layer sequentially stacked on the substrate and formed along a <011> direction. A current block portion has a p-type current blocking layer and an n-type current blocking layer. A p-type third clad layer simultaneously covers both the upper surfaces of the mesa stripe portion and the current blocking portion. The inclination angle as being acute angle of the side surface of the mesa stripe portion is close to the inclination angle of a (111)B crystal plane with respect to the (100) crystal plane and set at one of an angle larger than and an angle smaller than the inclination angle of the (111)B crystal plane.

Abstract: First and second diffraction grating layers are provided above a semiconductor substrate, and spaced from each other in an output direction of a beam. A connecting layer is flat and sandwiched between the first and second diffraction grating layers. An active layer is disposed above or below the first and second diffraction grating layers and the connecting layer. A cladding layer is disposed above the active layer or above the first and second diffraction grating layers and the connecting layer. A diffraction grating including the first and second diffraction grating layers has a plurality of slits penetrating from an upper surface to a lower surface and perpendicular to the output direction of the beam. The connecting layer is formed from two layers grown epitaxially in a direction perpendicular to the output direction of the beam. One of the two layers is formed of the same material as the first and second diffraction grating layers.

Abstract: An isotopomer absorption spectral analyzing apparatus and its method for precisely measuring the isotope ratio by substantially equalizing the absorption signal levels of different species of isotopes. In an isotopomer absorption spectral analyzing apparatus, a sample cell (21) capable of providing optical paths of different optical lengths is installed, optical beams A, B are caused to enter the sample cell (21) and travel along paths of different optical lengths, thereby determining the abundance ratio between species of isotopes in molecules from the ratio between intensities of signals corresponding to the species of isotopes.

Abstract: An n-type semiconductor substrate has a (100) crystal plane as an upper surface. A mesa stripe portion has a trapezoidal shape including an n-type first clad layer, an active layer and a p-type second clad layer sequentially stacked on the substrate and formed along a <011> direction. A current block portion has a p-type current blocking layer and an n-type current blocking layer. A p-type third clad layer simultaneously covers both the upper surfaces of the mesa stripe portion and the current blocking portion. The inclination angle as being acute angle of the side surface of the mesa stripe portion is close to the inclination angle of a (111)B crystal plane with respect to the (100) crystal plane and set at one of an angle larger than and an angle smaller than the inclination angle of the (111)B crystal plane.

Abstract: Disclosed is a semiconductor laser capable of preventing diffusion of a p-type dopant to an active layer while performing sufficient carrier blocking, even when Zn is used as a p-type dopant, and obtaining high emission efficiency and high output by minimizing light absorption in a p-type cladding layer. This semiconductor laser includes an active layer and p-type cladding layer on an n-type semiconductor substrate. The concentration distribution of a p-type dopant from the active layer to the p-type cladding layer has a maximum value at a distance of 50 to 250 nm from the end of the active layer.

Abstract: In an optical measuring apparatus, a laser beam is transferred to a diffraction grating so that the laser beam is spectrally separated into respective wavelength components. The wavelength components are sequentially guided into a polarizing optical element in which the respective wavelength component are separated into S and P polarized components, when the diffraction grating is rotated. The S and P polarized components of the respective wavelengths are detected by photodetectors and electrical signals from the photodetectors are supplied to a signal processing unit. In the signal processing unit, the electrical signals corresponding to the P and S components are corrected with a spectral efficiency characteristic of the grating, a percent loss characteristic of the polarizing element and photoelectro conversion characteristics of the photodetectors and the corrected signals are analyzed to obtain an absolute value of the laser energy for the respective wavelength.