Abstract: A method for fabricating a porous silica preform includes the steps of supplying fuel gas for generating an oxyhydrogen flame to a glass synthesizing burner; supplying Gas A containing silicon and Gas B containing fluorine to the burner; synthesizing glass particles; and depositing the glass particles around a starting rod, in which when glass particles are deposited directly on the starting rod, a supply of Gas A and a supply of Gas B supplied to the burner are adjusted so that a ratio of the number of fluorine atoms to the number of silicon atoms in the gas supplied to the burner satisfies the following Formula (1): {(number of F atoms)/(number of Si atoms)}?0.1??(1).

Abstract: An ytterbium-doped optical fiber of the present invention includes: a core which contains ytterbium, aluminum, and phosphorus and does not contain germanium; and a cladding which surrounds this core. The ytterbium concentration in the core in terms of ytterbium oxide is 0.09 to 0.68 mole percent. The molar ratio between the phosphorus concentration in the core in terms of diphosphorus pentoxide and the above ytterbium concentration in terms of ytterbium oxide is 3 to 30. The molar ratio between the aluminum concentration in the core in terms of aluminum oxide and the above ytterbium concentration in terms of ytterbium oxide is 3 to 32. The molar ratio between the above aluminum concentration in terms of aluminum oxide and the above phosphorus concentration in terms of diphosphorus pentoxide is 1 to 2.5.

Abstract: A processing method for suppressing photodarkening in an Yb-doped optical fiber, comprising: a first step of preparing the Yb-doped optical fiber by doping a core with Yb, and irradiating at least one of a gamma ray, a X-ray, or an electron beam onto the Yb-doped optical fiber with an energy greater than a light to be transmitted through the optical fiber when a laser is being oscillated; a second step of measuring a loss spectrum of an infrared region of the optical fiber after the first step, and selecting an optical fiber with the loss in a specific wavelength falling within a predetermined range; and a third step of treating the optical fiber selected in the second step in an atmosphere containing hydrogen to obtain an Yb-doped optical fiber with suppressed photodarkening.

Abstract: A manufacturing method of an optical communication module for manufacturing the optical communication module, including the sequentially performed steps of: (1) mounting a light-emitting element and a light-receiving element on a side surface of a sub-mount substrate and mounting the sub-mount substrate on a printed circuit board such that the light-emitting and -receiving directions of the light-emitting element and light-receiving element are parallel to the printed circuit board; (2) aligning an optical waveguide; and (3) dropping resin solution on an area of the sub-mount substrate including an optical waveguide end and the light-emitting element or the light-receiving element, and curing the resin solution. According to the present invention, it is possible to provide an optical communication module which can be made thin, small and cheap.

Abstract: Provided is a manufacturing method for an optical fiber preform of which the core is doped with a rare earth element. The method includes: depositing glass particles within a silica tube by the modified chemical vapor deposition method, the glass particles mainly consisting of silicon dioxide; adding the rare earth element and aluminum to the glass particles within the silica tube by the solution doping method; heating the silica tube while flowing a phosphorous-containing gas into the silica tube to sinter the glass particles within the silica tube while adding the phosphorous; and heating and collapsing the silica tube to which the rare earth element, the aluminum, and the phosphorous are added.

Abstract: Provided is a multi-cladding optical fiber which includes: a core with an average refractive index n1; and a cladding including an inner cladding with an average refractive index n2 formed on the periphery of the core, an intermediate cladding with an average refractive index n3 formed on the periphery of the inner cladding, and an outer cladding with an average refractive index n4 formed on the periphery of the intermediate cladding where n1>n2>n3>n4. Two or more axisymmetric modes exist in the core at a wavelength of the signal light; the two or more axisymmetric modes including a fundamental mode and at least a high-order mode. When the fiber is bent at a predetermined bending diameter, the high-order mode in the core disperses within the inner cladding due to coupling with an inner cladding mode, so that only the fundamental mode substantially propagates through the core.

Abstract: Provided is an ytterbium-doped optical fiber including a core containing at least ytterbium, aluminum and phosphorous and a clad surrounding the core, wherein a molar concentration of diphosphorus pentoxide with respect to phosphorus in the core is equal to a molar concentration of aluminum oxide with respect to aluminum in the core, wherein a ratio of a molar concentration of diphosphorus pentoxide with respect to phosphorus in the core to the molar concentration of ytterbium oxide with respect to ytterbium in the core is higher than or equal to 10 and lower than or equal to 30, and wherein a relative refractive index difference between the core and the clad is higher than or equal to 0.05% and lower than or equal to 0.30%.

Abstract: An ytterbium-doped optical fiber includes: a core which contains at least ytterbium, aluminum, and phosphorus; and a cladding which encircles the core, wherein an aluminum oxide equivalent concentration of the aluminum in the core is 0.2 mol % or more, a diphosphorus pentaoxide equivalent concentration of the phosphorus is higher than the aluminum oxide equivalent concentration, and the core either does not contain germanium or contains less than 1.1 mol % of germanium in a germanium dioxide equivalent concentration.

Abstract: An ytterbium-doped optical fiber of the present invention includes: a core which contains ytterbium, aluminum, and phosphorus and does not contain germanium; and a cladding which surrounds this core. The ytterbium concentration in the core in terms of ytterbium oxide is 0.09 to 0.68 mole percent. The molar ratio between the phosphorus concentration in the core in terms of diphosphorus pentoxide and the above ytterbium concentration in terms of ytterbium oxide is 3 to 30. The molar ratio between the aluminum concentration in the core in terms of aluminum oxide and the above ytterbium concentration in terms of ytterbium oxide is 3 to 32. The molar ratio between the above aluminum concentration in terms of aluminum oxide and the above phosphorus concentration in terms of diphosphorus pentoxide is 1 to 2.5.

Abstract: A method for fabricating a porous silica preform includes the steps of supplying fuel gas for generating an oxyhydrogen flame to a glass synthesizing burner; supplying Gas A containing silicon and Gas B containing fluorine to the burner; synthesizing glass particles; and depositing the glass particles around a starting rod, in which when glass particles are deposited directly on the starting rod, a supply of Gas A and a supply of Gas B supplied to the burner are adjusted so that a ratio of the number of fluorine atoms to the number of silicon atoms in the gas supplied to the burner satisfies the following Formula (1): {(number of F atoms)/(number of Si atoms)}?0.

Abstract: A rare-earth doped core multi-clad fiber includes a core that includes a rare-earth element and a plurality of cladding layers that surround the core. An outermost cladding of the plurality of cladding layers is made of a polymer cladding, the plurality of cladding layers have a polygonal inner cladding, and a shape of a boundary between a second cladding from the outside and the outermost cladding does not have two-fold rotational symmetry. As a result, it is possible to provide a rare-earth doped core multi-clad fiber for an optical amplifier and a fiber laser that has low skew and is inexpensive.

Abstract: A manufacturing method of an optical communication module for manufacturing the optical communication module, including the sequentially performed steps of: (1) mounting a light-emitting element and a light-receiving element on a side surface of a sub-mount substrate and mounting the sub-mount substrate on a printed circuit board such that the light-emitting and -receiving directions of the light-emitting element and light-receiving element are parallel to the printed circuit board; (2) aligning an optical waveguide; and (3) dropping resin solution on an area of the sub-mount substrate including an optical waveguide end and the light-emitting element or the light-receiving element, and curing the resin solution. According to the present invention, it is possible to provide an optical communication module which can be made thin, small and cheap.

Abstract: A method for fabricating a porous silica preform includes the steps of supplying fuel gas for generating an oxyhydrogen flame to a glass synthesizing burner; supplying Gas A containing silicon and Gas B containing fluorine to the burner; synthesizing glass particles; and depositing the glass particles around a starting rod, in which when glass particles are deposited directly on the starting rod, a supply of Gas A and a supply of Gas B supplied to the burner are adjusted so that a ratio of the number of fluorine atoms to the number of silicon atoms in the gas supplied to the burner satisfies the following Formula (1): {(number of F atoms)/(number of Si atoms)}?0.1 ??(1).

Abstract: A processing method for suppressing photodarkening in an Yb-doped optical fiber, comprising: a first step of preparing the Yb-doped optical fiber by doping a core with Yb, and irradiating at least one of a gamma ray, a X-ray, or an electron beam onto the Yb-doped optical fiber with an energy greater than a light to be transmitted through the optical fiber when a laser is being oscillated; a second step of measuring a loss spectrum of an infrared region of the optical fiber after the first step, and selecting an optical fiber with the loss in a specific wavelength falling within a predetermined range; and a third step of treating the optical fiber selected in the second step in an atmosphere containing hydrogen to obtain an Yb-doped optical fiber with suppressed photodarkening.

Abstract: An optical/electrical interconnect board includes a base material composing an electrical circuit; a plurality of light receiving/emitting units, each of the units being constituted by a light emitting element and a light receiving element packaged on the base material; and an optical fiber tape that connects the light emitting element to the light receiving element for each of the light receiving/emitting units, the optical fiber tape being formed by bringing together optical wires for the units in a side-by-side manner and coating with a first coating material.

Abstract: A method for fabricating a porous silica preform includes the steps of supplying fuel gas for generating an oxyhydrogen flame to a glass synthesizing burner; supplying Gas A containing silicon and Gas B containing fluorine to the burner; synthesizing glass particles; and depositing the glass particles around a starting rod, in which when glass particles are deposited directly on the starting rod, a supply of Gas A and a supply of Gas B supplied to the burner are adjusted so that a ratio of the number of fluorine atoms to the number of silicon atoms in the gas supplied to the burner satisfies the following Formula (1): {(number of F atoms)/(number of Si atoms)}?0.