Abstract: A preform manufacturing method of the present invention has a hole forming step of forming a plurality of holes in a glass body to produce a glass pipe, and a heating integration step of heating the glass pipe with core rods including core portions being inserted in the respective holes, thereby to implement integration of the core rods and the glass pipe. In the hole forming step, a peripheral hole out of the holes to be formed in the glass body is formed at a position determined in consideration of positional variation of the core portion before and after the integration.

Abstract: There is provided a method for producing a low-loss alkali metal-doped silica core optical fiber having excellent hydrogen resistance. The method for producing the optical fiber according to the present invention includes a drawing step of drawing an optical fiber preform in a drawing furnace to produce a silica glass-based optical fiber including a core region containing an alkali metal with an average concentration of 0.5 atomic ppm or more and a cladding region that surrounds the core region and a heating step of heating the optical fiber in a heating furnace through which the optical fiber drawn from the drawing furnace passes.

Abstract: There is provided a method for producing a low-loss alkali metal-doped silica core optical fiber having excellent hydrogen resistance. The method for producing the optical fiber according to the present invention includes a drawing step of drawing an optical fiber preform in a drawing furnace to produce a silica glass-based optical fiber including a core region containing an alkali metal with an average concentration of 0.5 atomic ppm or more and a cladding region that surrounds the core region and a heating step of heating the optical fiber in a heating furnace through which the optical fiber drawn from the drawing furnace passes.

Abstract: The present invention relates to an MCF with a structure for enabling an alignment work with higher accuracy. The MCF has a plurality of cores and a cladding. An outer peripheral shape of the cladding in a cross section of the MCF is comprised of a circumferential portion forming a circumference coincident with an outer periphery of the MCF, and a cut portion. The cut portion has a bottom portion and two contact portions provided on both sides of the bottom portion and projecting more than the bottom portion. When a side face of the MCF is viewed, the two contact portions have flattened faces and the flattened faces of the two contact portions extend along a longitudinal direction of the MCF with the bottom portion in between.

Abstract: A tool magazine includes a magazine arm and a gripper plate. The magazine arm has a tool pot to hold a tool. The magazine arm is pivotable around a pivotal axis such that the tool pot pivots around the pivotal axis. The gripper plate has at least one gripper to hold the tool at a holding position on a circular arc track along which the tool moves when the magazine arm pivots. The at least one gripper is open in a tangent direction of the circular arc track at the holding position.

Abstract: The present invention relates to an MCF and others with a structure for accurately aligning each of core arrangement directions of one or more MCFs to be fixed in a connector. Each of the MCFs has a marker as an index for rotational position. The ends of the MCFs are rotated while monitoring positions of the respective markers with a CCD camera or the like, whereby each of the core arrangement directions is aligned with a specific direction.

Abstract: An embodiment of the invention enables each core in an end face to be readily identified by observation of either one end face, regardless of the presence or absence of a twist of a pertinent MCF and difference of ends. In a cross section of the MCF, a core group constellation has symmetry but each core in a core group is identifiable by breaking of all types of symmetry in a common cladding, defined by a combination of the core group constellation with the common cladding, or, by making the fiber ends distinguishable.

Abstract: A preform manufacturing method of the present invention has a hole forming step of forming a plurality of holes in a glass body to produce a glass pipe, and a heating integration step of heating the glass pipe with core rods including core portions being inserted in the respective holes, thereby to implement integration of the core rods and the glass pipe. In the hole forming step, a peripheral hole out of the holes to be formed in the glass body is formed at a position determined in consideration of positional variation of the core portion before and after the integration.

Abstract: An embodiment relates to a method for manufacturing an optical module having an MCF and two connection components, and enables rotational alignment of the MCF to be implemented with high accuracy even in short-haul optical wiring. The MCF is arranged in a region between the two connection components while an end thereof projects from one connection component. As this arrangement state is maintained, array positions of cores in the projecting end are observed from a side face and the MCF is rotationally aligned by a rotation grasp jig grasping the projecting end to adjust the array positions of the cores, based on the observation result.

Abstract: Joint seal structure of robot, includes fitting end portion provided on an end portion of second member and fittingly inserted into tubular end portion of first member; a peripheral groove provided on an inner peripheral surface of tubular end portion to extend over an entire periphery; and an annular seal member accommodated into peripheral groove and in sealing contact with outer peripheral surface of fitting end portion. Fitting end portion has smaller diameter than body of second member, a stepped surface between body and fitting end portion faces an end surface of tubular end portion and located close to end surface of tubular end portion in an axial direction, and a gap is provided between stepped surface and end surface of tubular end portion such that gap extends over entire periphery, is opened to outside of first member and second member, and is expanded as gap extends radially outward.

Abstract: The present invention relates to an MCF with a structure for enabling an alignment work with higher accuracy. The MCF has a plurality of cores and a cladding. An outer peripheral shape of the cladding in a cross section of the MCF is comprised of a circumferential portion forming a circumference coincident with an outer periphery of the MCF, and a cut portion. The cut portion has a bottom portion and two contact portions provided on both sides of the bottom portion and projecting more than the bottom portion. When a side face of the MCF is viewed, the two contact portions have flattened faces and the flattened faces of the two contact portions extend along a longitudinal direction of the MCF with the bottom portion in between.

Abstract: An embodiment of the invention relates to a bent optical fiber manufacturing method for manufacturing a bent optical fiber in which a bent region with a desired radius of curvature is formed, while maintaining an optical transmission loss within a permissible range. The method has a pre-step of preparing an optical fiber comprised of silica-based glass, a bend portion forming step of forming a bend portion in a partial region of the optical fiber, and a laser light irradiating step of irradiating the thus-formed bend portion with laser light.

Abstract: There is provided a method for producing a low-loss alkali metal-doped silica core optical fiber having excellent hydrogen resistance. The method for producing the optical fiber according to the present invention includes a drawing step of drawing an optical fiber preform in a drawing furnace to produce a silica glass-based optical fiber including a core region containing an alkali metal with an average concentration of 0.5 atomic ppm or more and a cladding region that surrounds the core region and a heating step of heating the optical fiber in a heating furnace through which the optical fiber drawn from the drawing furnace passes.

Abstract: Joint seal structure of robot, includes fitting end portion provided on an end portion of second member and fittingly inserted into tubular end portion of first member; a peripheral groove provided on an inner peripheral surface of tubular end portion to extend over an entire periphery; and an annular seal member accommodated into peripheral groove and in sealing contact with outer peripheral surface of fitting end portion. Fitting end portion has smaller diameter than body of second member, a stepped surface between body and fitting end portion faces an end surface of tubular end portion and located close to end surface of tubular end portion in an axial direction, and a gap is provided between stepped surface and end surface of tubular end portion such that gap extends over entire periphery, is opened to outside of first member and second member, and is expanded as gap extends radially outward.

Abstract: A manufacturing method according to an embodiment of the invention includes a step of calculating Pj0.1 satisfying (62.6×JOH+1175)×Pj=0.1, where Pj is an optical power ratio at the wavelength 1383 nm of a portion corresponding to a cladding material of an MCF after drawn, and an outer diameter ratio Pcc0.1 of core portions to core rods to obtain Pj0.1. The core rods have an outer diameter 2R0.1 satisfying the condition that a ratio Pcc is not less than the ratio Pcc0.1, and the cladding material has holes formed in a diameter larger by C (not less than 0.15 mm and not more than 1.5 mm) than the outer diameter of the core rods.

Abstract: An optical fiber manufacturing method includes a drawing step and a slow cooling step. In the slow cooling step, an optical fiber passes through a heating furnace having a temperature which is set such that in at least 70% of a region from a first position at which a glass outer diameter of the optical fiber becomes less than 500% of a final outer diameter to a second position at which a temperature T of the optical fiber becomes 1400° C., an actual temperature of the optical fiber is within ±100° C. of a target temperature Tt(n) for each position n. The target temperature Tt(n) is a temperature at which a fictive temperature Tf(n+1) of a core at a position n+1 determined by calculation using the recurrence formula “Tf(n+1)=T(n)+(Tf(n)?T(n))exp(??t(T(n)))” starting from a fictive temperature Tf(0) of the optical fiber at the first position n=0 is lowest.

Abstract: An inexpensive low-attenuation optical fiber 1 suitable for use as an optical transmission line in an optical access network is a silica based glass optical fiber and includes a core 11 including the center axis, an optical cladding 12 surrounding the core, and a jacket 13 surrounding the optical cladding. The core contains GeO2 and has a relative refractive index difference ?core, based on the optical cladding, greater than or equal to 0.35% and less than or equal to 0.50% and has a refractive index volume v greater than or equal to 0.045 ?m2 and less than or equal to 0.095 ?m2. The jacket has a relative refractive index difference ?J greater than or equal to 0.03% and less than or equal to 0.20%. Glass constituting the core has a fictive temperature higher than or equal to 1400° C. and lower than or equal to 1590° C. Residual stress in the core is compressive stress that has an absolute value greater than or equal to 5 MPa.

Abstract: An inexpensive low-attenuation optical fiber 1 suitable for use as an optical transmission line in an optical access network is a silica based glass optical fiber and includes a core 11 including the center axis, an optical cladding 12 surrounding the core, and a jacket 13 surrounding the optical cladding. The core contains GeO2 and has a relative refractive index difference ?core, based on the optical cladding, greater than or equal to 0.35% and less than or equal to 0.50% and has a refractive index volume v greater than or equal to 0.045 ?m2 and less than or equal to 0.095 ?m2. The jacket has a relative refractive index difference ?J greater than or equal to 0.03% and less than or equal to 0.20%. Glass constituting the core has a fictive temperature higher than or equal to 1400° C. and lower than or equal to 1590° C. Residual stress in the core is compressive stress that has an absolute value greater than or equal to 5 MPa.

Abstract: An inexpensive low-attenuation optical fiber 1 suitable for use as an optical transmission line in an optical access network is a silica based glass optical fiber and includes a core 11 including the center axis, an optical cladding 12 surrounding the core, and a jacket 13 surrounding the optical cladding. The core contains GeO2 and has a relative refractive index difference ?core, based on the optical cladding, greater than or equal to 0.35% and less than or equal to 0.50% and has a refractive index volume v greater than or equal to 0.045 ?m2 and less than or equal to 0.095 ?m2. The jacket has a relative refractive index difference ?J greater than or equal to 0.03% and less than or equal to 0.20%. Glass constituting the core has a fictive temperature higher than or equal to 1400° C. and lower than or equal to 1590° C. Residual stress in the core is compressive stress that has an absolute value greater than or equal to 5 MPa.

Abstract: An optical fiber having excellent strength that can be manufactured at low cost, as well as a method for making such optical fiber, is provided. An optical fiber 1 is a silica-based optical fiber comprising a core 11, an optical cladding 12 surrounding the core 11, and a jacketing region 13 surrounding the optical cladding 12 and having a uniform composition throughout from the internal circumference to the outer circumference. A compressive strained layer having a residual compressive stress is provided at the outermost circumference of the jacketing region 13.