Abstract: A multicore fiber includes cores located at vertexes of a polygonal ring and a cladding including sub medium regions and covering the cores. A refractive index of the cladding is lower than a refractive index of the cores and higher than a refractive index of the sub medium regions. The sub medium regions are arranged at positions to reduce a crosstalk between adjacent cores of the cores.

Abstract: An optical fiber end processing method includes fixing two portions of an optical fiber, heating and fusing the optical fiber between the two fixed portions, to form a first heat fusion region, heating and fusing the optical fiber fixed between the two fixed portions unit while fixing the two fixed portions, moving a heat fusion unit from a side of the first heat fusion region toward a base end side of the optical fiber, and pushing a heat fusion portion of the optical fiber in a direction of shortening a length of the heat fusion portion, to form a second heat fusion region continuous to the first heat fusion region and in which the air holes of the optical fiber disappear; and removing the first heat fusion region by cutting the optical fiber within the second heat fusion region after the second heat fusion forming.

Abstract: An optical fiber that has no bubbles in the ultraviolet ray curable resin filled inside the air holes to seal the end parts thereof, an end part processing method of the optical fiber, and an end part processing apparatus of the optical fiber, are provided. In an end part processing method of an optical fiber that is comprised of a core and a cladding formed around the core, the cladding having a refraction index lower than that of the core and has a plurality of air holes formed therein along the axis of the core, wherein the end part process of the optical fiber is to form sealed portions on the ends of the air holes by sealing them with ultraviolet ray curable resin, the method is characterized in that the sealed portion is formed by heating the end of the optical fiber.

Abstract: A multicore fiber includes cores located at vertexes of a polygonal ring and a cladding including sub medium regions and covering the cores. A refractive index of the cladding is lower than a refractive index of the cores and higher than a refractive index of the sub medium regions. The sub medium regions are arranged at positions to reduce a crosstalk between adjacent cores of the cores.

Abstract: An optical fiber end processing method includes fixing two portions of an optical fiber, heating and fusing the optical fiber between the two fixed portions, to form a first heat fusion region, heating and fusing the optical fiber fixed between the two fixed portions unit while fixing the two fixed portions, moving a heat fusion unit from a side of the first heat fusion region toward a base end side of the optical fiber, and pushing a heat fusion portion of the optical fiber in a direction of shortening a length of the heat fusion portion, to form a second heat fusion region continuous to the first heat fusion region and in which the air holes of the optical fiber disappear; and removing the first heat fusion region by cutting the optical fiber within the second heat fusion region after the second heat fusion forming.

Abstract: An optical fiber that permits, even when the cladding outer diameter thereof is smaller than 125 ?m, an eased splicing with other optical fiber using a general-purpose ferrule, is provided. The optical fiber comprises: a first optical fiber having a first core and a first cladding having a cladding outer diameter smaller than 125 ?m, wherein the first cladding has a plurality of air holes that extend longitudinally along the axis of the first core; a second optical fiber having a second core to be spliced to the first core, and a second cladding having a cladding outer diameter larger than the outer diameter of the first cladding, wherein the second cladding is to be spliced to the first cladding; and a fusion splice formed between the end of the first optical fiber and the end of the second optical fiber by fusion.

Abstract: An optical fiber that has no bubbles in the ultraviolet ray curable resin filled inside the air holes to seal the end parts thereof, an end part processing method of the optical fiber, and an end part processing apparatus of the optical fiber, are provided. In an end part processing method of an optical fiber that is comprised of a core and a cladding formed around the core, the cladding having a refraction index lower than that of the core and has a plurality of air holes formed therein along the axis of the core, wherein the end part process of the optical fiber is to form sealed portions on the ends of the air holes by sealing them with ultraviolet ray curable resin, the method is characterized in that the sealed portion is formed by heating the end of the optical fiber.

Abstract: An optical connector according to the present invention comprises a ferrule and a V-groove board connected to the ferrule, wherein a first optical fiber and a second optical fiber being butt jointed in a V-groove formed in the V-groove board so as to be interconnected; the second optical fiber is connected to the first optical fiber through a refractive index matching material of cross-link curing type applied to an end surface on the V-groove board side of the first optical fiber; and spaces are provided in the V-groove so as to relax stress loaded on the refractive index matching material of cross-link curing type.

Abstract: An optical connector according to the present invention comprises a ferrule and a V-groove board connected to the ferrule, wherein a first optical fiber and a second optical fiber being butt jointed in a V-groove formed in the V-groove board so as to be interconnected; the second optical fiber is connected to the first optical fiber through a refractive index matching material of cross-link curing type applied to an end surface on the V-groove board side of the first optical fiber; and spaces are provided in the V-groove so as to relax stress loaded on the refractive index matching material of cross-link curing type.

Abstract: An optical connector having: a ferrule into which a first optical fiber is inserted; an optical fiber connector disposed at an back end of the ferrule; and a cross-linkable refractive index matching member attached onto an end face on a back end side of the first optical fiber. The end face on the back end side of the first optical fiber and an end face of a second optical fiber to be inserted into the optical fiber connector from a back end side thereof are to be connected by a butting connection. The cross-linkable refractive index matching member is formed such that a cross-linkable refractive index matching agent is coated on the end face on the back end side of the first optical fiber, and the coated agent is cross-linked and hardened.

Abstract: An optical connector having: a ferrule into which a first optical fiber is inserted; an optical fiber connector disposed at an back end of the ferrule; and a cross-linkable refractive index matching member attached onto an end face on a back end side of the first optical fiber. The end face on the back end side of the first optical fiber and an end face of a second optical fiber to be inserted into the optical fiber connector from a back end side thereof are to be connected by a butting connection. The cross-linkable refractive index matching member is formed such that a cross-linkable refractive index matching agent is coated on the end face on the back end side of the first optical fiber, and the coated agent is cross-linked and hardened.

Abstract: A rotary joint for polarization plane maintaining optical fibers which can couple two polarization plane maintaining optical fibers to each other while maintaining the polarization plane maintaining property. The rotary joint comprises a rotary member, a fixed member, two optical fiber collimators and a 1/2 wavelength plate for coupling a polarization plane maintaining optical fiber connected to the rotary member with another polarization plane maintaining optical fiber connected to the fixed member, and gears for rotating the 1/2 wavelength plate at a speed equal to one half the rotational speed of the polarization plane maintaining optical fiber on the rotary member side.