Abstract: A multicore polarization-maintaining fiber 10 includes a plurality of cores 11, a cladding 12 surrounding the plurality of cores 11, and a plurality of stress applying parts 15 provided sandwiching the plurality of cores 11 in a region surrounded by the outer circumferential surface of the cladding 12. The cross sectional area of the stress applying part 15 is greater than the cross sectional area of the core 11. Stress applying parts 15 of the plurality of stress applying parts 15 are disposed in a first direction, and stress applying parts 15 of the plurality of stress applying parts 15 are disposed in a second direction different from the first direction.

Abstract: A multicore polarization-maintaining fiber 10 includes a plurality of cores 11, a cladding 12 surrounding the plurality of cores 11, and a plurality of stress applying parts 15 provided sandwiching the plurality of cores 11 in a region surrounded by the outer circumferential surface of the cladding 12. The cross sectional area of the stress applying part 15 is greater than the cross sectional area of the core 11. Stress applying parts 15 of the plurality of stress applying parts 15 are disposed in a first direction, and stress applying parts 15 of the plurality of stress applying parts 15 are disposed in a second direction different from the first direction.

Abstract: A polarization-maintaining optical fiber of the present invention includes a core, a pair of stress-applying parts provided on both sides of the core, and a cladding surrounding the core and the stress-applying parts, and is used in a wavelength range of 400 to 680 nm. The diameter of the cladding is 125 ?m, the diameter of the stress-applying part is 33 to 37 ?m, a distance between the pair of stress-applying parts is 8.6 to 15.4 ?m, a relative refractive index difference between the core and the cladding is 0.35 to 0.45%, and a cut-off wavelength is less than or equal to 400 nm.

Abstract: A low-loss optical fiber over wide wavelength range includes a transmission loss of less than or equal to 40 dB/km in a whole wavelength range of 400-1400 nm, and being manufactured by drawing an optical fiber preform including a core composed of a silica glass having a hydroxyl-group concentration of less than or equal to 1 ppm and a cladding composed of a silica glass having a fluorine concentration of more than or equal to 3.2 wt %.

Abstract: The polarization-maintaining fiber of the invention includes a core (1) made of germanium doped silica glass; a stress-applying part (3) made of boron doped silica glass; a cladding (2) made of pure silica glass; and a polyimide coating layer (4) with a thickness of 10 ?m or less that surrounds the outer periphery of the cladding (2).

Abstract: A low-loss optical fiber over wide wavelength range includes a transmission loss of less than or equal to 40 dB/km in a whole wavelength range of 400-1400 nm, and being manufactured by drawing an optical fiber preform including a core composed of a silica glass having a hydroxyl-group concentration of less than or equal to 1 ppm and a cladding composed of a silica glass having a fluorine concentration of more than or equal to 3.2 wt %.

Abstract: The polarization-maintaining fiber of the invention includes a core (1) made of germanium doped silica glass; a stress-applying part (3) made of boron doped silica glass; a cladding (2) made of pure silica glass; and a polyimide coating layer (4) with a thickness of 10 ?m or less that surrounds the outer periphery of the cladding (2).

Abstract: A dispersion compensating optical fiber for NZ-DSFs, includes: an uncovered dispersion compensating optical fiber; a double-layered resin coating disposed around the uncovered dispersion compensating optical fiber; and an outer coating layer having a thickness of 3 to 7 ?m, containing silicone in an amount of 1 to 5% by weight, and disposed around the double-layered resin coating. The outer diameter of the uncovered dispersion compensating optical fiber is in a range from 90 to 125 ?m, an outer diameter of the dispersion compensating optical fiber is in a range from 180 to 250 ?m, and the amount of silicone contained in the outer coating layer is determined such that an adhesive property of the outer coating layer is 1 gf/mm or less.

Abstract: A radiation resistant single-mode optical fiber has a core and a cladding, each made of fluorine-doped silica glass, in which a chlorine concentration of the core is at least 0.01 ppm, a relative refractive index difference of the core based on the refractive index for silica is between ?0.30% and ?0.10%, a relative refractive index difference of the core based on the refractive index for the cladding is between 0.3% and 0.5%, a cutoff wavelength is 1.27 ?m or below, and a bending loss at a wavelength of 1.3 ?m and a bending diameter of 20 mm is 0.5 dB/m or less.

Abstract: A polarization-maintaining optical fiber comprises: a core; a pair of stress-applying parts disposed one at each side of the core; and a cladding which surrounds the core and the stress-applying parts; wherein when the polarization-maintaining optical fiber is used at a wavelength of 0.81 ?m to 0.87 ?m, a cut-off wavelength measured with a fiber length of 2 m is longer than the wavelength used and polarization crosstalk when a fiber having a length of 1,000 m is wound on a reel having a diameter of 40 mm is equal to or less than ?35 dB/100 m.

Abstract: A multi-core optical fiber apparatus is disclosed. The multi-core optical fiber apparatus includes a cladding comprising quartz and a plurality of cores embedded in the cladding. Each of the cores has a diameter (D) ranging from 1.3 ?m to 2.0 ?m, a numerical aperture (NA) from 0.35 to 0.45 and a refractive index profile factor (?) from 2.0 to 4.0. A center of each of the cores has a germanium content of 20 wt % to 30 wt %. An interval between adjacent cores is 3.0 ?m or more.

Abstract: A higher order mode dispersion compensating fiber includes an optical fiber and a first loss layer which is provided within the fiber and which attenuates a lower order mode propagating through the optical fiber while not attenuating a higher order mode which is higher than the lower order mode. A dispersion compensating fiber mode converter for a higher order fiber includes a single mode fiber; a higher order mode dispersion compensating fiber; and a fused and extended portion which has been formed by fusing and extending the single mode fiber and the higher order mode fiber. The fused and extended portion converts between the LP01 mode of the single mode fiber and the LP02 mode of the higher order mode dispersion compensating fiber.

Abstract: A multi-core optical fiber apparatus is disclosed. The multi-core optical fiber apparatus includes a cladding comprising quartz and a plurality of cores embedded in the cladding. Each of the cores has a diameter (D) ranging from 1.3 ?m to 2.0 ?m, a numerical aperture (NA) from 0.35 to 0.45 and a refractive index profile factor (a) from 2.0 to 4.0. A center of each of the cores has a germanium content of 20 wt % to 30 wt %. An interval between adjacent cores is 3.0 ?m or more.

Abstract: A radiation resistant single-mode optical fiber has a core and a cladding, each made of fluorine-doped silica glass, in which a chlorine concentration of the core is at least 0.01 ppm, a relative refractive index difference of the core based on the refractive index for silica is between ?0.30 and ?0.10%, a relative refractive index difference of the core based on the refractive index for the cladding is between 0.3% and 0.5%, a cutoff wavelength is 1.27 ?m or below, and a bending loss at a wavelength of 1.3 ?m and a bending diameter of 20 mm is 0.5 dB/m or less.

Abstract: A hole-assisted holey fiber is provided. The holey fiber includes a core region; a cladding region around the core region, and a plurality of holes in the cladding region around the core region. The core region has a higher refractive index than that of the cladding region. The holes form an inner hole layer and an outer hole layer, and the inner hole layer has the same number of holes as the number of the holes in the outer hole layer. The outer layer holes are provided in locations in which inner holes are absent when viewed from the center of the core region, and holes defining the same layer have the same diameter. A distance ?1 from a center of the core region to a center of an inner hole and a distance ?2 from the center of the core region to a center of an outer hole satisfy the relationship ?1<?2, and a diameter d1 of an inner hole and a diameter d2 of an outer hole satisfy the relationship d1?d2.

Abstract: A connection method for a photonic crystal fiber for connecting the photonic crystal fiber and a fiber to be connected, the photonic crystal fiber including a cladding region having a number of microholes and a core region having a same refractive index as that of the cladding region, includes the steps of: abutting respective end faces of the photonic crystal fiber and the fiber to be connected each other; after the abutting, performing a main discharge in which an abutted portion is heated by an electric discharge under a first condition; and after the main discharge, performing an additional discharge in which the connection portion is heated by an electric discharge at least once under a second condition to increase a splice strength.

Abstract: A higher order mode dispersion compensating fiber includes an optical fiber and a first loss layer which is provided within the fiber and which attenuates a lower order mode propagating through the optical fiber while not attenuating a higher order mode which is higher than the lower order mode. A dispersion compensating fiber mode converter for a higher order fiber includes a single mode fiber; a higher order mode dispersion compensating fiber; and a fused and extended portion which has been formed by fusing and extending the single mode fiber and the higher order mode fiber. The fused and extended portion converts between the LP01 mode of the single mode fiber and the LP02 mode of the higher order mode dispersion compensating fiber.

Abstract: A higher order mode dispersion compensating fiber includes an optical fiber and a first loss layer which is provided within the fiber and which attenuates a lower order mode propagating through the optical fiber while not attenuating a higher order mode which is higher than the lower order mode. A dispersion compensating fiber mode converter for a higher order fiber includes a single mode fiber; a higher order mode dispersion compensating fiber; and a fused and extended portion which has been formed by fusing and extending the single mode fiber and the higher order mode fiber. The fused and extended portion converts between the LP01 mode of the single mode fiber and the LP02 mode of the higher order mode dispersion compensating fiber.

Abstract: A dispersion-compensated optical fiber which does not cause an increase in a loss if it is wound in a small reel and has a stable temperature characteristics is provided, wherein, in a wavelength range from. A dispersion-compensated optical fiber is formed such that, in at least a wavelength between 1.53 to 1.63 ?m, a bending loss of with a 20 mm bending diameter is 5 dB/m or lower, a wavelength dispersion is ?120 ps/nm/km or lower, a cut-off wavelength under a usage condition is 1.53 ?m or lower, an outer diameter of the cladding is 80 to 100 ?m, an outer diameter of a coating is 160 to 200 ?m, and a viscosity of a surface of a coating resin is 10 gf/mm or lower. It is set such that b/a is 1.5 to 3.5, c/b is 1.2 to 2.0, a radius of a core is 4 to 8 ?m, ?1 is +1.6% to +2.6%, ?2 is ?0.30% to ?1.4%, and ?3 is ?0.30% to +1.0%. Young's modulus of a first coating layer is 0.15 kgf/mm2 or lower and its thickness is 20 to 30 ?m.

Abstract: A polarization-maintaining optical fiber comprises: a core; a pair of stress-applying parts disposed one at each side of the core; and a cladding which surrounds the core and the stress-applying parts; wherein when the polarization-maintaining optical fiber is used at a wavelength of 0.81 ?m to 0.87 ?m, a cut-off wavelength measured with a fiber length of 2 m is longer than the wavelength used and polarization crosstalk when a fiber having a length of 1,000 m is wound on a reel having a diameter of 40 mm is equal to or less than ?35 dB/100 m.