Abstract: A non-contact direction changer includes: a guide groove that guides an optical fiber and changes a direction of advancement of the optical fiber from a first direction to a second direction; a bottom ejection opening at a bottom of the guide groove; and one or more side ejection openings on at least one of opposite side surfaces of the guide groove. A fluid is ejected into the guide groove through the bottom ejection opening. A fluid is ejected into the guide groove through the one or more side ejection openings.

Abstract: A method for manufacturing an optical fiber includes: gripping a preform by a gripper that includes an aligner; forming a bare fiber by melting the preform in a melting furnace; cooling the bare fiber by blowing gas in a cooler; applying a resin and coating an outer circumference of the bare fiber; curing the resin; acquiring input information that changes a flow rate of the gas blown to the bare fiber in the cooler; and adjusting based on the input information an entry position of the bare fiber into the cooler by controlling the aligner and moving the preform.

Abstract: An optical fiber manufacturing method includes: drawing an optical fiber preform to form a bare optical fiber; cooling the bare optical fiber by a non-contact direction changer; adjusting a temperature of the bare optical fiber in a temperature adjusting unit disposed downstream of the non-contact direction changer and upstream of a coating unit; disposing, in the coating unit, an uncured coating layer that comprises a resin precursor on an outer periphery of the bare optical fiber; and curing the uncured coating layer in a curing unit.

Abstract: An optical fiber manufacturing method includes: drawing an optical fiber preform to form a bare optical fiber; cooling the bare optical fiber; coating an uncured coating layer that includes a resin precursor on an outer periphery of the bare optical fiber; curing the uncured coating layer to form a semi-cured coating layer; further curing the semi-cured coating layer; and cooling the semi-cured coating layer by at least one non-contact direction changer between the curing of the uncured coating layer and the curing of the semi-cured coating layer.

Abstract: A non-contact direction changer includes: a guide groove that guides an optical fiber and changes a direction of advancement of the optical fiber from a first direction to a second direction; a bottom ejection opening at a bottom of the guide groove; and one or more side ejection openings on at least one of opposite side surfaces of the guide groove. A fluid is ejected into the guide groove through the bottom ejection opening. A fluid is ejected into the guide groove through the one or more side ejection openings.

Abstract: An optical fiber manufacturing method includes: drawing an optical fiber preform to form a bare optical fiber; cooling the bare optical fiber by a non-contact direction changer; adjusting a temperature of the bare optical fiber in a temperature adjusting unit disposed downstream of the non-contact direction changer and upstream of a coating unit; disposing, in the coating unit, an uncured coating layer that comprises a resin precursor on an outer periphery of the bare optical fiber; and curing the uncured coating layer in a curing unit.

Abstract: An optical fiber manufacturing method includes: drawing an optical fiber preform to form a bare optical fiber; cooling the bare optical fiber; coating an uncured coating layer that includes a resin precursor on an outer periphery of the bare optical fiber; curing the uncured coating layer to form a semi-cured coating layer; further curing the semi-cured coating layer; and cooling the semi-cured coating layer by at least one non-contact direction changer between the curing of the uncured coating layer and the curing of the semi-cured coating layer.

Abstract: A multicore optical fiber (1) includes a plurality of cores (11 to 16) and a cladding (20) surrounding the outer circumferential surfaces of the cores (11 to 16). In the plurality of cores of the multicore optical fiber (1), a skew value (S) between a pair of cores is expressed by a predetermined expression. The multicore optical fiber (1) is bent in a specific bending direction, in which in all of the combinations of the pairs of cores in the plurality of cores, the pair of cores has the maximum absolute value of the skew value found by the expression and the skew value of the pair of cores is a minimum value.

Abstract: A multicore fiber according to an embodiment of the present invention includes a plurality of cores and a cladding that encloses the plurality of the cores. The external form of the cladding in a cross section is formed of an arc portion that is formed in an arc shape relative to the center axis of the cladding and a non-arc portion that is pinched between two ends of the arc portion and not formed in an arc shape relative to the center axis of the cladding. The non-arc portion is formed with a pair of projections projecting from two ends of the arc portion on the opposite side of the center axis relative to a straight line connecting the both ends of the arc portion and one or more of recesses pinched between the pair of the projections.

Abstract: A multicore optical fiber (1) includes a plurality of cores (11 to 16) and a cladding (20) surrounding the outer circumferential surfaces of the cores (11 to 16). In the plurality of cores of the multicore optical fiber (1), a skew value (S) between a pair of cores is expressed by a predetermined expression.

Abstract: A plurality of clad rods, and a clad tube, an arrangement process for arranging the plurality of core rods and the plurality of clad rods in a tube of the clad tube, in a state in which distances between center axes of the adjacent core rods become equal to each other and a state in which parts of outer circumferential surfaces in the adjacent rods contact, and an integration process for integrating the clad tube and the plurality of core rods and the plurality of clad rods arranged in the tube, wherein a ratio of a total cross-sectional area of a direction orthogonal to a length direction in the plurality of core rods and the plurality of clad rods with respect to an internal cross-sectional area of the tube of a direction orthogonal to a length direction in the clad tube is 0.84 or more.

Abstract: A measuring method of a longitudinal distribution of bending loss of an optical fiber includes calculating an arithmetical mean value I(x) from two backscattering light intensities of two backscattering light at a position x obtained by bidirectional OTDR measurement of the optical fiber; and obtaining a bending loss value at the position x from a mode field diameter 2W(x) and a relative refractive index difference ?(x) at the position x calculated from the arithmetical mean value.

Abstract: A multicore fiber according to the present invention includes a plurality of cores and a cladding enclosing the plurality of the cores. The plurality of the cores has two cores or greater forming a first plurality of cores linearly arranged to form a first row on one side based on a plane passed through the center axis of the cladding and three cores or greater forming a second plurality of cores arranged in parallel with the first plurality of the cores to form a second row on the other side based on the plane. The cores configuring the first plurality of the cores and the cores configuring the second plurality of the cores are disposed on lines orthogonal to the plane.

Abstract: A multicore fiber includes a plurality of cores and a cladding that encloses the plurality of the cores. The plurality of the cores is arranged and disposed on a linear line passed through the center of the cladding. A difference in the cutoff wavelength between an outer core located at the outermost position and an inner core located next to the outer core is set at a wavelength of 100 nm or less.

Abstract: A multicore fiber includes a plurality of cores and a cladding surrounding the plurality of cores. The plurality of cores is arranged and disposed on a linear line passed through the center of the cladding. A pair of cores is included. The pair of the cores is located adjacent to each other, and has different core diameters in a first direction in which the plurality of cores is arranged on the linear line. A ratio of a core diameter in the first direction to a core diameter in a second direction orthogonal to the first direction is different between the pair of the cores.

Abstract: An optical fiber cable includes a tubular sheath and a plurality of optical fibers disposed in the space of the sheath as the optical fibers are bent. In the plurality of optical fibers, at least one optical fiber is a multicore fiber. The multicore fiber satisfies an expression RPk<RLo, or RHi<RPk, where a bending radius at which the crosstalk of the multicore fiber becomes the worst is defined as RPk, a bending radius of the multicore fiber at a lowest temperature in operating temperature limits is defined as RLo, and a bending radius of the multicore fiber at a highest temperature in the operating temperature limits is defined as RHi.

Abstract: A multicore fiber according to an aspect of the present invention includes a plurality of cores and a cladding surrounding the plurality of the cores. In this multicore fiber, a pair of cores is arranged and disposed on a linear line passed through the center of the cladding, the pair of the cores being adjacent to each other and having refractive indexes varied differently from the cladding to the cores.

Abstract: An optical fiber cable includes a tubular sheath and a plurality of optical fibers disposed in the space of the sheath as the optical fibers are bent. In the plurality of optical fibers, at least one optical fiber is a multicore fiber. The multicore fiber satisfies an expression RPk<RLo, or RHi<RPk, where a bending radius at which the crosstalk of the multicore fiber becomes the worst is defined as RPk, a bending radius of the multicore fiber at a lowest temperature in operating temperature limits is defined as RLo, and a bending radius of the multicore fiber at a highest temperature in the operating temperature limits is defined as RHi.

Abstract: For example, of a first intensity distribution waveform WF1 indicated by a distance distribution of an intensity of light which returns to one end of a core of a multicore fiber, and a second intensity distribution waveform WF2 indicated by a distance distribution of an intensity of light which returns to the other end of the core, the second intensity distribution waveform WF2 is inverted. Further, for example, an inverted intensity distribution waveform WF3 which is inverted and the first intensity distribution waveform WF1 which is not inverted are added.

Abstract: A multicore fiber includes a plurality of cores, a cladding that encloses the plurality of the cores, and a marker disposed in the cladding. The plurality of the cores is arranged and disposed on a linear line passed through the center of the cladding. The marker is disposed along the length direction of the cladding on a portion on which the marker does not overlap the cores in a first direction in which the plurality of the cores is arranged on the linear line and does not overlap the core in a second direction orthogonal to the first direction.