Abstract: A manufacturing method includes forming one or more first holes in a cladding rod, inserting a first glass rod into each of the one or more first holes, heating the cladding rod together with the inserted first glass rod to integrate the first glass rod and the cladding rod and to form an intermediate preform, forming one or more second holes in the intermediate preform, inserting a second glass rod into each of the one or more second holes, and heating the intermediate preform together with the inserted second glass rod to integrate the second glass rod and the intermediate preform.

Abstract: An MCF according to the disclosure has a structure preventing deterioration in quality of optical transmission signals. The MCF comprises cores, a common cladding, and a coating. Any of the cores has a coating leakage loss of 0.01 dB/km or more at a wavelength within a wavelength range of from 850 nm to 1700 nm. The coating includes a leaked light propagation suppressive coating layer having a first optical property or a second optical property to light with a wavelength within a wavelength range of from 850 nm to 1700 nm or from 1260 nm to 1625 nm. The first optical property is defined by, as an attenuation index of the light, an absorbance per 1 ?m thickness being 0.1 dB or more. The second optical property is defined by a product of absorbance per 1 ?m thickness and a thickness being 0.1 dB or more.

Abstract: A cutting tool includes: a shank part; and a cutting part provided at one end of the shank part. The cutting part includes a first region provided at one end of the cutting tool, and a second region located closer to a center of the cutting tool than the first region. Abrasive grains adhere to the first region and the second region. An average grain diameter of the abrasive grains in the second region is smaller than an average grain diameter of the abrasive grains in the first region.

Abstract: A manufacturing method includes forming one or more first holes in a cladding rod, inserting a first glass rod into each of the one or more first holes, heating the cladding rod together with the inserted first glass rod to integrate the first glass rod and the cladding rod and to form an intermediate preform, forming one or more second holes in the intermediate preform, inserting a second glass rod into each of the one or more second holes, and heating the intermediate preform together with the inserted second glass rod to integrate the second glass rod and the intermediate preform.

Abstract: Provided is an optical fiber manufacturing method that uses a low-cost large optical fiber preform having high precision. The optical fiber manufacturing method includes at least a positioning step of positioning core rods in a hollow carbon pipe that contains carbon as a main component, a soot preform preparation step of filling a gap between the carbon pipe and the core rods with silica powder that contains SiO2 as a main component, thereby producing a soot preform, a consolidating step of introducing the soot preform into a furnace and consolidating the silica powder, thereby producing a transparent intermediate preform from the soot preform, an extraction step of extracting the transparent intermediate preform from the carbon pipe, and a drawing step of drawing the transparent intermediate preform, thereby manufacturing an optical fiber.

Abstract: An MCF according to the disclosure has a structure preventing deterioration in quality of optical transmission signals. The MCF comprises cores, a common cladding, and a coating. Any of the cores has a coating leakage loss of 0.01 dB/km or more at a wavelength within a wavelength range of from 850 nm to 1700 nm. The coating includes a leaked light propagation suppressive coating layer having a first optical property or a second optical property to light with a wavelength within a wavelength range of from 850 nm to 1700 nm or from 1260 nm to 1625 nm. The first optical property is defined by, as an attenuation index of the light, an absorbance per 1 ?m thickness being 0.1 dB or more. The second optical property is defined by a product of absorbance per 1 ?m thickness and a thickness being 0.1 dB or more.

Abstract: A method for manufacturing a multicore optical fiber includes a step of forming ring-shaped closed-end holes to axially extend from a first end toward a second end of a glass rod; a step of heating bottom parts of the ring-shaped closed-end holes and softening center rods surrounded by the ring-shaped closed-end holes; a step of pulling out the center rods toward a side of the first end, forming columnar closed-end holes from the ring-shaped closed-end holes, and treating the glass rod as a cladding material; a connecting step of connecting a supporting pipe to the first end; an inserting step of inserting core rods into the columnar closed-end holes after the connecting step; and a drawing step of drawing the cladding material and the core rods while heating a portion near the second end and integrating the cladding material and the core rods after the inserting step.

Abstract: An optical connector manufacturing method includes inserting a protrusion of a fixing jig into a positioning hole in an end face of a cladding of an optical fiber and restraining rotation of the optical fiber, the positioning hole extending in an optical axis direction, the optical fiber being inserted in a through hole in a connector ferrule and protruding from an end face of the connector ferrule; and securing the optical fiber to the connector ferrule, with the protrusion of the fixing jig inserted in the positioning hole.

Abstract: The disclosure provides a method of manufacturing a multicore optical fiber comprising a plurality of cores and a common cladding covering each of the plurality of cores and having a non-circular cross-sectional shape capable of passive alignment. The method includes providing an optical fiber preform having a cross-sectional shape delimited by a line obtained by replacing a part of a circumference with one chord or two chords parallel to each other, and applying a drawing tension to one end of the optical fiber preform to draw a multicore optical fiber. An aspect ratio x of the cladding defined by a ratio of a radius of a circle defining the circumference to a distance from the center of the circle to the chord and a drawing tension y are set so that the common cladding has a depression at the center of a plane corresponding to the one or each of the two chords.

Abstract: A method and an apparatus for measuring a profile of a beam output from a randomly-coupled multi-core fiber are provided. An apparatus includes a light source, a measurement unit, and an analysis unit. Light output from the light source is input in one or more of a plurality of spatial modes of the fiber at an input end of the fiber. The measurement unit measures a sum of intensity profiles of individual light components output from respective ones of the plurality of spatial modes by averaging a component of interference between the plurality of spatial modes in a beam profile of combined light output from the plurality of spatial modes at an output end of the fiber. The analysis unit calculates an MFD and/or Aeff of the fiber based on the sum of the intensity profiles of the individual light components obtained by the measurement unit.

Abstract: There is provided a method for producing a multicore optical fiber while depressurizing holes in a common cladding tube. A production method for a multicore optical fiber includes a preform forming step of forming a common cladding tube having a plurality of holes extending between a first end and a second end, an end-face working step of digging the common cladding tube from the second end to a predetermined depth to forming a third end, a connection step of connecting a glass tube to the second end, an insertion step of inserting core rods into the holes to the third end, a sealing step of sealing the first end, and a drawing step of spinning the multicore optical fiber while depressurizing the holes through the glass tube and combining the common cladding tube and the core rods from the first end.

Abstract: There is provided a method for producing a multicore optical fiber while reducing the mass of a glass block to be connected to a common cladding tube. A production method for a multicore optical fiber includes in order, a preform forming step of forming a common cladding tube having a plurality of holes extending between a first end and a second end, an insertion step of inserting core rods in the holes in a state in which end portions of the core rods are recessed from the first end, a heat shrinkage step of reducing a diameter of the first end by heating, a sealing step of sealing the holes by connecting a glass block to the first end, and a drawing step of depressurizing insides of the holes from the second end and performing spinning from the first end while combining the common cladding tube and the core rods.

Abstract: Provided is a method for producing a multicore optical fiber (MCF) in which variations in positions of cores relative to the outer shape of the MCF are small. The method includes: an integrating step of heating a common cladding tube and a core rods, thereby integrating the tube with the core rods to form a core-cladding composite body including a plurality of cores and a common cladding and having a noncircular cross-sectional shape; an outline detecting step of detecting the outline of the composite body; an optical fiber preform forming step of machining the outer circumferential surface of the composite body using results obtained in the outline detecting step to form the preform having a flat surface; and a drawing step of drawing one end of the preform under heating to obtain the MCF. Also provided is a MCF for which a rotation alignment operation is easily performed.

Abstract: Provided is a method for producing a multicore optical fiber (MCF) in which variations in positions of cores relative to the outer shape of the MCF are small. The method includes: an integrating step of heating a common cladding tube and a core rods, thereby integrating the tube with the core rods to form a core-cladding composite body including a plurality of cores and a common cladding and having a noncircular cross-sectional shape; an outline detecting step of detecting the outline of the composite body; an optical fiber preform forming step of machining the outer circumferential surface of the composite body using results obtained in the outline detecting step to form the preform having a flat surface; and a drawing step of drawing one end of the preform under heating to obtain the MCF. Also provided is a MCF for which a rotation alignment operation is easily performed.

Abstract: A method for manufacturing a multicore optical fiber includes a step of forming ring-shaped closed-end holes to axially extend from a first end toward a second end of a glass rod; a step of heating bottom parts of the ring-shaped closed-end holes and softening center rods surrounded by the ring-shaped closed-end holes; a step of pulling out the center rods toward a side of the first end, forming columnar closed-end holes from the ring-shaped closed-end holes, and treating the glass rod as a cladding material; a connecting step of connecting a supporting pipe to the first end; an inserting step of inserting core rods into the columnar closed-end holes after the connecting step; and a drawing step of drawing the cladding material and the core rods while heating a portion near the second end and integrating the cladding material and the core rods after the inserting step.

Abstract: Provided is an optical fiber manufacturing method that uses a low-cost large optical fiber preform having high precision. The optical fiber manufacturing method includes at least a positioning step of positioning core rods in a hollow carbon pipe that contains carbon as a main component, a soot preform preparation step of filling a gap between the carbon pipe and the core rods with silica powder that contains SiO2 as a main component, thereby producing a soot preform, a consolidating step of introducing the soot preform into a furnace and consolidating the silica powder, thereby producing a transparent intermediate preform from the soot preform, an extraction step of extracting the transparent intermediate preform from the carbon pipe, and a drawing step of drawing the transparent intermediate preform, thereby manufacturing an optical fiber.

Abstract: A method and an apparatus for measuring a profile of a beam output from a randomly-coupled multi-core fiber are provided. An apparatus includes a light source, a measurement unit, and an analysis unit. Light output from the light source is input in one or more of a plurality of spatial modes of the fiber at an input end of the fiber. The measurement unit measures a sum of intensity profiles of individual light components output from respective ones of the plurality of spatial modes by averaging a component of interference between the plurality of spatial modes in a beam profile of combined light output from the plurality of spatial modes at an output end of the fiber. The analysis unit calculates an MFD and/or Aeff of the fiber based on the sum of the intensity profiles of the individual light components obtained by the measurement unit.

Abstract: A coupled-core multi-core fiber in which an inter-core distance is stabilized is manufactured. A method of manufacturing a coupled-core multi-core fiber includes forming a second cladding base material by depositing glass particulates on an outer periphery of a first cladding base material and sintering the glass particulates. The first cladding base material has a hydroxyl group concentration that is less than or equal to 10 ppb; obtaining a ground rod by grinding an outer periphery of the second cladding base material; and forming holes in the first cladding base material in the ground rod, inserting a core base material into each of the holes, and obtaining an assembly.

Abstract: An optical connector manufacturing method includes inserting a protrusion of a fixing jig into a positioning hole in an end face of a cladding of an optical fiber and restraining rotation of the optical fiber, the positioning hole extending in an optical axis direction, the optical fiber being inserted in a through hole in a connector ferrule and protruding from an end face of the connector ferrule; and securing the optical fiber to the connector ferrule, with the protrusion of the fixing jig inserted in the positioning hole.

Abstract: There is provided a method for producing a multicore optical fiber while reducing the mass of a glass block to be connected to a common cladding tube. A production method for a multicore optical fiber includes in order, a preform forming step of forming a common cladding tube having a plurality of holes extending between a first end and a second end, an insertion step of inserting core rods in the holes in a state in which end portions of the core rods are recessed from the first end, a heat shrinkage step of reducing a diameter of the first end by heating, a sealing step of sealing the holes by connecting a glass block to the first end, and a drawing step of depressurizing insides of the holes from the second end and performing spinning from the first end while combining the common cladding tube and the core rods.