Abstract: A core region is doped with an impurity. A first cladding region is formed in a layered structure around the core region, including a microstructure. A second cladding region is formed in a layered structure around the first cladding region, including a homogeneous material. A relative refractive-index difference ?1 between the core region and the second cladding region is equal to or more than 0.4% and equal to or less than 1.0%.

Abstract: An optical fiber in which the macro-bending loss is lowered while an MFD is maintained large, and a waveguide including the optical fiber. The optical fiber includes a core region doped with an impurity; a first cladding region formed as a layer around the core region and including holes as microstructures; and a second cladding region formed as a layer around the first cladding region and made of a homogeneous material. A relative refractive-index difference ?1 between the core region and the second cladding region is equal to or higher than 0.01% and lower than 0.3%. A total cross-sectional area of the holes in the first cladding region with respect to a total cross-sectional area of the core region, the first cladding region, and the second cladding region is equal to or smaller than 20%. A waveguide is formed using the optical fiber.

Abstract: An optical fiber includes a core region having a first refractive index and a cladding region having a second refractive index lower than the first refractive index on an outer circumference of the core region. The cladding region includes four holes formed to have a four-fold rotational symmetry with respect to a center axis around the core region in a longitudinal direction, such that a zero-dispersion wavelength is 900 nm to 1150 nm and a cutoff wavelength is equal to or shorter than 950 nm.

Abstract: A polarization-maintaining optical fiber includes a core region and a cladding region formed around the core region. The cladding region has a refractive index lower than a refractive index of the core region. A refractive index profile of the core region is either one of a step shaped or a concave shaped. The cladding region includes two holes formed in such a manner that a shortest distance from the core region is virtually zero at locations in opposite to each other across the core region.

Abstract: The present invention can easily realize an optical fiber and an optical transmission line that can propagate a light in a single mode while lowering a macro-bending loss and a PMD at the same time. An optical fiber 1 according to the present invention includes a cladding region 8 having a refractive index lower than that of a core region 2 on outer circumference of the core region 2. The cladding region 8 includes a first cladding region 3 in which a plurality of sub-medium regions 5a to 5d and 6a to 6h are arranged in multilayer.

Abstract: The present invention can easily realize an optical fiber and an optical transmission line that can propagate a light in a single mode while lowering a macro-bending loss against a small-diameter bending. An optical fiber 1 according to the present invention includes a first cladding region 3 having a refractive index lower than a refractive index of a core region 2 on outer circumference of the core region 2. Sub-medium regions 5a to 5f, 6a to 6f are arranged in multilayer in the first cladding region 3, which have a refractive index lower than a refractive index of a main-medium region of the first cladding region 3. The sub-medium regions 5a to 5f having a circular shape with a lateral cross section of a diameter d1 is arranged in an inner cladding area 3a of the first cladding region 3, and the sub-medium regions 6a to 6f having a circular shape with a lateral cross section of a diameter d2 (>d1) is arranged in an outer cladding area 3b of the first cladding region 3.

Abstract: The present invention provides an optical fiber of a high nonlinear characteristic which has low dispersion values in a wide wavelength region in the vicinity of a wavelength of 1550 nm. An excellent optical signal processing apparatus is realized by using this optical fiber, such as an optical wavelength converter and a pulse compressor. The optical fiber has characteristics; a dispersion slope at the wavelength of 1550 nm of ?0.01 to 0.01 ps/nm2/km, an absolute value of dispersion at the wavelength of 1550 nm of 10 ps/nm/km or less, and a nonlinear constant at the wavelength of 1550 nm of 30×10?10/W or more. A polarization retaining maintaining members are uniquely applied.

Abstract: A silica material having a higher purity than a cylindrical preform formed of a silica material is deposited on at least one of an inner side and an outer side of the preform to fabricate a cylindrical intermediate member. A part of the cylindrical intermediate member including at least a part of the preform is removed to fabricate a high-purity silica tube. A plurality of the high-purity silica tubes is bundled with a core rod arranged at a center axis of a bundle of the high-purity silica tubes, and the bundle of the high-purity silica tubes with the core rod arranged at the center axis is drawn to obtain a microstructured optical fiber.

Abstract: An optical fiber includes a first core with a first refractive index located in a central portion of the optical fiber; a second core with a second refractive index located in an outer periphery of the first core; a third core with a third refractive index located in an outer periphery of the second core; and a cladding with a fourth refractive index located in an outer periphery of the third core, where among the refractive indices, the first one>the third one>the fourth one>the second one. The absolute value of dispersion at the wavelength of 1550 nm is not more than 20 ps/nm/km. The effective area at the wavelength is not more than 15 ?m2. The nonlinear constant n2/Aeff at the wavelength of 1550 nm is equal to or more than 25×10?10/W.

Abstract: The present invention provides an optical fiber of a high nonlinear characteristic which has low dispersion values in a wide wavelength region in the vicinity of a wavelength of 1550 nm. An excellent optical signal processing apparatus is realized by using this optical fiber, such as an optical wavelength converter and a pulse compressor. The optical fiber has characteristics; a dispersion slope at the wavelength of 1550 nm of ?0.01 to 0.01 ps/nm2/km, an absolute value of dispersion at the wavelength of 1550 nm of 10 ps/nm/km or less, and a nonlinear constant at the wavelength of 1550 nm of 30×10?10/W or more. A polarization retaining maintaining members are uniquely applied.

Abstract: An optical fiber includes a first core with a first refractive index located in a central portion of the optical fiber; a second core with a second refractive index located in an outer periphery of the first core; a third core with a third refractive index located in an outer periphery of the second core; and a cladding with a fourth refractive index located in an outer periphery of the third core, where among the refractive indices, the first one>the third one>the fourth one>the second one. The absolute value of dispersion at the wavelength of 1550 nm is not more than 20 ps/nm/km. The effective area at the wavelength is not more than 15 ?m2. The nonlinear constant n2/Aeff at the wavelength of 1550 nm is equal to or more than 25×10?10/W.