Abstract: Brightness profile data are extracted based on side view image data of an optical fiber, machine learning is performed by using teacher data indicating a correspondence relationship between brightness profile in a radial direction of the optical fiber and a type of the optical fiber, the teacher data being created based on the brightness profile data, a classification model is created to be able to determine the type of the optical fiber for an arbitrary optical fiber based on the brightness profile data indicating brightness profile in the radial direction of the arbitrary optical fiber, and the type of the optical fiber is determined for each of a pair of optical fibers by using the classification model based on the brightness profile data that is extracted based on side view image data of the pair of optical fibers as a target. The pair of optical fibers are fusion-spliced based on a fusion condition that is set in accordance with a combination of respective determined types of the optical fibers.

Abstract: A surface-emitting laser apparatus includes: a surface-emitting laser element; and a driving apparatus supplying a modulation-driving current to the surface-emitting laser element. The modulation-driving current is intensity-modulated to vary across a value of a bias current. The number of lateral modes of laser oscillation of the surface-emitting laser element changes from one to three at maximum in accordance with a value of the modulation-driving current. Among changing currents at which number of the lateral modes of the laser oscillation of the surface-emitting laser element changes, if a first changing current is defined at which the number of the lateral mode of the laser oscillation changes from one to two, the driving apparatus supplies the modulation-driving current to the surface-emitting laser element. The modulation-driving current is set so that a value of the first changing current is not between the bias current and a maximum value of the modulation-driving current.

Abstract: A surface-emitting laser apparatus includes: a surface-emitting laser element; and a driving apparatus supplying a modulation-driving current to the surface-emitting laser element. The modulation-driving current is intensity-modulated to vary across a value of a bias current. The number of lateral modes of laser oscillation of the surface-emitting laser element changes from one to three at maximum in accordance with a value of the modulation-driving current. Among changing currents at which number of the lateral modes of the laser oscillation of the surface-emitting laser element changes, if a first changing current is defined at which the number of the lateral mode of the laser oscillation changes from one to two, the driving apparatus supplies the modulation-driving current to the surface-emitting laser element. The modulation-driving current is set so that a value of the first changing current is not between the bias current and a maximum value of the modulation-driving current.

Abstract: An optical phase modulator includes a main Mach-Zehnder interferometer having first and second main optical waveguide path arms, whose initial phase difference in the used wavelength is ?, a first sub Mach-Zehnder interferometer having first and second sub optical waveguide path arms that are formed in the first main optical waveguide path arm, whose initial phase difference in the used wavelength is 0, and a second sub Mach-Zehnder interferometer having third and fourth sub optical waveguide path arms that are formed in the second main optical waveguide path arm, and whose initial phase difference in the used wavelength is 0. Of each of the main optical waveguide path arms and the sub optical waveguide path arms, at least the portions where high-frequency electrodes are formed are constructed using semiconductor waveguide paths, and reduce the effects of frequency chirping caused by an orthogonal component due to light absorption in the semiconductor.

Abstract: The optical phase modulator of the present invention comprises: a main Mach-Zehnder interferometer having first and second main optical waveguide path arms, and whose initial phase difference in the used wavelength is ?; a first sub Mach-Zehnder interferometer having first and second sub optical waveguide path arms that are formed in said first main optical waveguide path arm, and whose initial phase difference in the used wavelength is 0; and a second sub Mach-Zehnder interferometer having third and fourth sub optical waveguide path arms that are formed in said second main optical waveguide path arm, and whose initial phase difference in the used wavelength is 0.

Abstract: A surface emitting laser is provided with an upper reflecting mirror having a photonic crystal structure with a point defect at the center, and emits a laser beam from the side of a lower reflecting mirror. An upper electrode is formed on the point defect at the center, and element resistance is reduced. A material transparent to a wavelength of the laser beam is used for a substrate. The emission efficiency is improved by reducing the element resistance of the photonic crystal surface emitting laser.

Abstract: A surface emitting semiconductor laser comprises a semiconductor substrate; a lamination structure including a lower multilayer film reflecting mirror, an active layer, and an upper multilayer film reflecting mirror formed on the semiconductor substrate; and an upper electrode and a lower electrode for supplying an electric power to the active layer. The upper multilayer film reflecting mirror has a refractive index having a two-dimensional periodic distribution within a lamination plane except a predetermined region in the lamination plane.

Abstract: A vertical-cavity surface-emitting laser (VCSEL) includes a substrate, and a layer structure including a first reflector, an active layer, and a second reflector, which are consecutively layered on the substrate, and a plurality of holes arranged in a two-dimensional structure periodically within a layer plane except for a specified area of the layer structure, wherein a pair of holes sandwiching therebetween the specific area and opposing each other have a dimension or shape different from the dimension or shape of others of the holes.

Abstract: To provide a photonic crystal semiconductor device which enables various kinds of optical devices having a photonic crystal structure which is readily formed using a semiconductor and a semiconductor manufacturing process, and a manufacturing method thereof. The object can be achieved by a photonic crystal structure, including a lower DBR layer 1, a core layer 2, an upper DBR layer 3, and a dielectric multilayer film 6 which are sequentially laminated from an n-InP substrate 11 side, a plurality of holes 9 formed in the direction of a film thickness in the core layer 2 and the upper DBR layer 3, and a line defect portion 10 with none of the plurality of holes formed therein and disposed between the plurality of holes 9, wherein the line defect portion 10 serves as an optical waveguide.

Abstract: A surface emitting laser is provided with an upper reflecting mirror having a photonic crystal structure with a point defect at the center, and emits a laser beam from the side of a lower reflecting mirror. An upper electrode is formed on the point defect at the center, and element resistance is reduced. A material transparent to a wavelength of the laser beam is used for a substrate. The emission efficiency is improved by reducing the element resistance of the photonic crystal surface emitting laser.

Abstract: A DFB semiconductor laser device includes a diffraction grating extending parallel to a laser cavity. The diffraction grating has ununiform structure wherein some of the corrugation patterns of diffraction grating are omitted periodically, the diffraction grating has different duty ratio between the area near the front facet of the laser cavity and the area near the rear facet, or the length of the diffraction grating is smaller than the cavity length and the width of the diffraction grating reduces in the vicinity of the rear end of the diffraction grating down to zero at the rear end.

Abstract: To provide a photonic crystal semiconductor device which enables various kinds of optical devices having a photonic crystal structure which is readily formed using a semiconductor and a semiconductor manufacturing process, and a manufacturing method thereof. The object can be achieved by a photonic crystal structure, including a lower DBR layer 1, a core layer 2, an upper DBR layer 3, and a dielectric multilayer film 6 which are sequentially laminated from an n-InP substrate 11 side, a plurality of holes 9 formed in the direction of a film thickness in the core layer 2 and the upper DBR layer 3, and a line defect portion 10 with none of the plurality of holes formed therein and disposed between the plurality of holes 9, wherein the line defect portion 10 serves as an optical waveguide.

Abstract: A DFB semiconductor laser device including an n-type semiconductor substrate and a layer structure, overlying the semiconductor substrate, including an active layer, a compound semiconductor layer constituting a diffraction grating and overlying the active layer, and an embedding layer embedding the diffraction grating, wherein said at least one of the compound semiconductor layer and the embedding layer has a carrier density of 7×1017 to 2×1018 cm?3.

Abstract: A method for forming a set of DFB lasers includes the steps of forming active layers having different peak gain wavelengths, measuring the peak gain wavelengths of the active layers, and forming diffraction gratings having periods based on the measured peak gain wavelengths, the periods allowing the detuning amount of the DFB laser device to fall within a design value.

Abstract: A DFB semiconductor laser device includes a diffraction grating extending parallel to a laser cavity. The diffraction grating has ununiform structure wherein some of the corrugation patterns of diffraction grating are omitted periodically, the diffraction grating has different duty ratio between the area near the front facet of the laser cavity and the area near the rear facet, or the length of the diffraction grating is smaller than the cavity length and the width of the diffraction grating reduces in the vicinity of the rear end of the diffraction grating down to zero at the rear end.

Abstract: A DFB semiconductor laser device including an n-type semiconductor substrate and a layer structure, overlying the semiconductor substrate, including an active layer, a compound semiconductor layer constituting a diffraction grating and overlying the active layer, and an embedding layer embedding the diffraction grating, wherein said at least one of the compound semiconductor layer and the embedding layer has a carrier density of 7×1017 to 2×1018 cm−3.

Abstract: A method for forming a set of DFB lasers includes the steps of forming active layers having different peak gain wavelengths, measuring the peak gain wavelengths of the active layers, and forming diffraction gratings having periods based on the measured peak gain wavelengths, the periods allowing the detuning amount of the DFB laser device to fall within a design value.