Abstract: An optical fiber suitable for use in a single fiber or multifiber optical connector or array is structured with a core region and a cladding region surrounding the core region, and exhibits a bending loss of a fundamental mode of the fiber at a wavelength ? is lower than 0.1 dB/m at a diameter of 15 mm, a mode-field diameter of the fundamental mode at an end of the fiber at the wavelength ? is between 8.0 ?m and 50 ?, and a bending loss of a first higher-order mode at the wavelength ? is higher than 1 dB/m at a diameter of 30 mm. The fiber may be multistructured, wherein the cladding region comprises a main medium and a plurality of sub medium regions therein to form a spatially uniform average refractive index.

Abstract: An optical module comprises a multiplexer for combining a signal and a pump radiation and having an output coupled to an optical fiber and a signal over the optical fiber with the pump lightwave that has a frequency three times of that of the signal and phase index equal to that of the signal. Phase matching between the pump and signal is realized for example by employing a microstructured optical fiber as the optical fiber.

Abstract: A microstructured optical fiber is structured with a core region and a plurality of cladding regions surrounding the core region. Chromatic dispersion is relatively flat over a broad wavelength range with a small effective area, without need for air holes that are unacceptably small. An enlarged effective core area is obtained by selectively closing the holes in the innermost cladding, which holes are smaller and easier to close than the holes in other regions.

Abstract: An optical fiber suitable for use in a single fiber or multifiber optical connector or array is structured with a core region and a cladding region surrounding the core region, and exhibits a bending loss of a fundamental mode of the fiber at a wavelength ? is lower than 0.1 dB/m at a diameter of 15 mm, a mode-field diameter of the fundamental mode at an end of the fiber at the wavelength ? is between 8.0 ?m and 50 ?, and a bending loss of a first higher-order mode at the wavelength ? is higher than 1 dB/m at a diameter of 30 mm. The fiber may be multistructured, wherein the cladding region comprises a main medium and a plurality of sub medium regions therein to form a spatially uniform average refractive index.

Abstract: The present invention provides an optical fiber which has a hollow portion extending along the axis and which reduces degradation of the optical characteristics, and a production method thereof. An optical fiber includes a hollow core portion, and a cladding portion which surrounds the hollow core portion. The refractive index of the hollow core portion is lower than that of the cladding portion. The hollow core portion is closed at both ends of the optical fiber so as to form sealed portions. The sealed portions are formed by, for example, heating the optical fiber and softening the cladding portion. This prevents foreign material and the like from entering the hollow core portion. Ferrules of optical connectors are attached to both end faces of the optical fiber.

Abstract: In an optical fiber including a core region and cladding regions of not less than three layers which surrounds the core region in order, each of said cladding regions has a mean refractive index different from those of the adjacents regions,at least one of the cladding regions has a lower mean refractive index than both adjacent regions, and at least one cladding region is provided with a plurality of sub medium regions each having a refractive index lower than a main medium constituting this cladding region.

Abstract: A microstructured optical fiber is structured with a core region and a cladding region surrounding the core region. A cross section of the fiber portion conforms to a translationally symmetric lattice, a center of each sub medium region in the outer region coinciding with respective lattice points, and a plurality of sub medium regions in the inner region having centers that are offset from respective lattice points.

Abstract: The present invention discloses an optical transmission line constructing method comprising the steps of connecting a plurality of optical fibers differing from each other in terms of a transmission characteristic; making inspection light incident on an entrance end of the connected plurality of optical fibers; detecting, on the entrance end side, respective return light components of the inspection light occurring at individual positions of the plurality of optical fibers in its longitudinal direction; evaluating a characteristic information distribution of return light in the longitudinal direction of the plurality of optical fibers; and constructing an optical transmission line according to a result of the evaluation.

Abstract: An optical fiber has a section of the first kind having a chromatic dispersion not less than a given positive value x and a negative chromatic dispersion slope at a given wavelength and a section of the second kind has a chromatic dispersion not more than −x and a positive chromatic dispersion slope at the same wavelength. Another optical fiber has a chromatic dispersion higher than a positive value x and a negative chromatic dispersion slope at a given wavelength band.

Abstract: An optical fiber has a section of the first kind having a chromatic dispersion not less than a given positive value x and a negative chromatic dispersion slope at a given wavelength and a section of the second kind has a chromatic dispersion not more than −x and a positive chromatic dispersion slope at the same wavelength. Another optical fiber has a chromatic dispersion higher than a positive value x and a negative chromatic dispersion slope at a given wavelength band.

Abstract: An optical fiber suitable for use in a single fiber or multifiber optical connector or array is structured with a core region and a cladding region surrounding the core region, and exhibits a bending loss of a fundamental mode of the fiber at a wavelength &lgr; is lower than 0.1 dB/m at a diameter of 15 mm, a mode-field diameter of the fundamental mode at an end of the fiber at the wavelength &lgr; is between 8.0 &mgr;m and 50 &lgr;, and a bending loss of a first higher-order mode at the wavelength &lgr; is higher than 1 dB/m at a diameter of 30 mm. The fiber may be multistructured, wherein the cladding region comprises a main medium and a plurality of sub medium regions therein to form a spatially uniform average refractive index.

Abstract: A microstructured optical fiber is structured with a core region and a plurality of cladding regions surrounding the core region. Chromatic dispersion is relatively flat over a broad wavelength range with a small effective area, without need for air holes that are unacceptably small. An enlarged effective core area is obtained by selectively closing the holes in the innermost cladding, which holes are smaller and easier to close than the holes in other regions.

Abstract: An optical module comprises a multiplexer for combining a signal and a pump radiation and having an output coupled to an optical fiber and a signal over the optical fiber with the pump lightwave that has a frequency three times of that of the signal and phase index equal to that of the signal. Phase matching between the pump and signal is realized for example by employing a microstructured optical fiber as the optical fiber.

Abstract: In an optical fiber including a core region and a cladding region surrounding said core region in a cross section and having a cross-sectional structure in which a plurality of regions constituted by sub mediums are arranged in main mediums, at least one of refractive indices of the main mediums and the sub mediums are changed in a radial direction.

Abstract: Provided are an optical transmission line including a connected part of the optical fibers having different refractive index profiles, wherein at least one of the optical fibers has a hollow region, and a method for connecting such optical fibers, wherein connection loss in a connection of such optical fibers is reduced. In the case of connecting an optical fiber 1, which does not have a hollow region and which consists of a core region 3 and a cladding region 4, and an optical fiber 2, which consists of a hollow core region 5 and a cladding region 6 having a plurality of refractive index variation parts 7 which extend along optical fiber 2, matching oil M is first injected into the connecting end portion of the hollow core region 5 to be connected with the optical fiber 1. The matching oil M is a substance that has a matched refractive index greater than the refractive index of the material which forms the cladding region 6.

Abstract: In an optical fiber composed of a core region and a cladding region surrounding the core region and having a plurality of regions made of sub mediums having refractive indices different from a refractive index of a main medium disposed in a main medium constituting this cladding region, these regions made of the sub mediums are arranged in one given or a plurality of a given circular annular regions and the centers of the regions made of the sub mediums in respective circular annular regions are arranged on the same circumference centered at the center of the core.

Abstract: A microstructured optical fiber is structured with a core region and a cladding region surrounding the core region. A cross section of the fiber portion conforms to a translationally symmetric lattice, a center of each sub medium region in the outer region coinciding with respective lattice points, and a plurality of sub medium regions in the inner region having centers that are offset from respective lattice points.

Abstract: An optical fiber has a core region and a cladding region surrounding the core region. The core region and the cladding region are made of a base material containing silica glass as a principal component. A plurality of holes extending along an axial direction are arranged at least in the cladding region. In the optical fiber, the base material has a hydroxyl mole fraction of not less than 10 ppm, or a fluorine content of not less than 0.2% by weight.

Abstract: In an optical fiber having a core region and a cladding region which surrounds the core region, wherein a plurality of regions made of sub mediums having refractive index different from that of the main medium constituting the cladding region are spaced apart in cross section of the cladding region and the mean refractive index of the core region is lower than that of the cladding region, the sub-medium regions are regularly arranged in the radial direction of said optical fiber such that the light having given wavelength, propagation coefficient and electric field distribution propagates along the fiber axis and has not less than 50% of a total propagating power in the core region, and this arrangement does not have translational symmetry in cross section.

Abstract: In an optical fiber having a core region and a cladding region, surrounding the core region, comprising a main medium having different refractive indices from the main medium and spaced apart in the main medium, the core region comprises a central core region having a hollow portion disposed at the center of the core region and an outer core region surrounding the central core region having a mean refractive index higher than the central core region, and the core region has a higher mean refractive index than the cladding region.