Abstract: A method of producing a glass preform including: forming a porous glass soot configured by an inner deposition soot deposited on a start material and an outer deposition soot deposited outside the inner deposition soot; and sintering, after the forming, the porous glass soot while doping with fluorine to form a glass body including an inner glass portion and an outer glass layer. An amount of the fluorine, with which the inner deposition soot is doped at the sintering, is equal to or more than 0 g/cm3 and less than an amount of the fluorine with which the outer deposition soot is doped.

Abstract: A method of producing a glass preform including: forming a porous glass soot configured by an inner deposition soot deposited on a start material and an outer deposition soot deposited outside the inner deposition soot; and sintering, after the forming, the porous glass soot while doping with fluorine to form a glass body including an inner glass portion and an outer glass layer. An amount of the fluorine, with which the inner deposition soot is doped at the sintering, is equal to or more than 0 g/cm3 and less than an amount of the fluorine with which the outer deposition soot is doped.

Abstract: A hole-assisted optical fiber includes a core portion and a cladding portion that includes an inner cladding layer, an outer cladding layer, and holes formed around the core portion. A diameter of the core portion is 3 ?m to 9.8 ?m, a relative refractive index difference of the core portion relative to the outer cladding layer is 0.11% to 0.45%, an outside diameter of the inner cladding layer is 53 ?m or less, a relative refractive index difference of the inner cladding layer relative to the outer cladding layer is a negative value, ?0.30% or more, a diameter of each hole is 2.4 ?m to 4.0 ?m, a hole occupancy rate is 17% to 48%, a bending loss at a wavelength of 1625 nm when bent at a radius of 5 mm is 1 dB/turn or less, and a cut-off wavelength is 1550 nm or less.

Abstract: A method of manufacturing an optical fiber preform includes forming a porous body that is made of glass particles and includes a first region and a second region formed on an outer circumference of the first region, performing a first heat treatment on the porous body under an atmosphere containing a fluorine gas, performing a second heat treatment on the porous body after the first heat treatment at a higher temperature than that of the first heat treatment to form a transparent glass body, and forming a cladding portion on an outer circumference of the transparent glass body.

Abstract: An optical fiber preform manufacturing method includes: supporting a drilling jig in a radial direction of a preform that is cylinder-shaped; moving the drilling jig in a longitudinal direction of the preform; and forming a plurality of slits each extending in the longitudinal direction and each directed from an outer side of the preform toward a center the preform, and a plurality of holes each extending in the longitudinal direction and each connecting with an end of one of the plurality of slits in a depth direction of the one of the plurality of slits.

Abstract: An optical fiber preform manufacturing method includes: supporting a drilling jig in a radial direction of a preform that is cylinder-shaped; moving the drilling jig in a longitudinal direction of the preform; and forming a plurality of slits each extending in the longitudinal direction and each directed from an outer side of the preform toward a center the preform, and a plurality of holes each extending in the longitudinal direction and each connecting with an end of one of the plurality of slits in a depth direction of the one of the plurality of slits.

Abstract: A relative refractive index difference ?1 between a center core region and a cladding layer is 0.30% to 0.35%, a relative refractive index difference ?2 between an outer core layer and the cladding layer is ?0.10% to ?0.04%, and ?1:?2 is 2.5:1 to 7.5:1. A diameter of the center core region is 9.0 ?m to 10.5 ?m, and a ratio of diameters of the center core region and the outer core layer is 0.20 to 0.35. A cutoff wavelength is 1310 nm or shorter, a zero dispersion wavelength is 1285 nm to 1345 nm, and at a wavelength of 1550 nm, an MFD is 10.5 ?m or larger, a transmission loss is 0.185 dB/km or lower, and a bending loss is 15 dB/m or lower.

Abstract: A relative refractive index difference ?1 between a center core region and a cladding layer is 0.30% to 0.35%, a relative refractive index difference ?2 between an outer core layer and the cladding layer is ?0.10% to ?0.04%, and ?1:?2 is 2.5:1 to 7.5:1. A diameter of the center core region is 9.0 ?m to 10.5 ?m, and a ratio of diameters of the center core region and the outer core layer is 0.20 to 0.35. A cutoff wavelength is 1310 nm or shorter, a zero dispersion wavelength is 1285 nm to 1345 nm, and at a wavelength of 1550 nm, an MFD is 10.5 ?m or larger, a transmission loss is 0.185 dB/km or lower, and a bending loss is 15 dB/m or lower.

Abstract: An inner core has a first refractive index. An outer core having a second refractive index lower than the first refractive index is formed on outer circumference of the inner core. A cladding having a refractive index that is higher than the second refractive index and lower than the first refractive index is formed on outer circumference of the outer core. A diameter of the inner core is enlarged, the second refractive index is decreased, and a center core having a refractive index lower than the first refractive index is formed at a center of the inner core, to increase an effective core area while maintaining wavelength dispersion and bending loss.

Abstract: Optical fibers to form an optical transmission line suitable for WDM transmission in a wide-spreading wavelength band, having the following characteristics and parameters: a dispersion in absolute value of 0.5 ps/nm/km to 9 ps/nm/km in a wavelength band of 1430 nm to 1625 nm, a dispersion slope in absolute value of 0.04 ps/nm2/km or less at a wavelength of 1550 nm, a mode field diameter of 7 ?m or less at a wavelength of 1550 nm and a cable cutoff wavelength of less than 1430 nm; core 11 surrounded by cladding 7, core 11 being at least two-layered (first layer 1 at the center and second layer 2 surrounding the first layer; relative refractive index of glass layer ?1 with reference to the cladding being adjusted to not less than 0.6 but not more than 1.6%, relative refractive index of second layer ?2 with reference to the cladding being adjusted to a negative value.

Abstract: Optical fibers to form an optical transmission line suitable for WDM transmission in a wide-spreading wavelength band, having the following characteristics and parameters: a dispersion in absolute value of 0.5 ps/nm/km to 9 ps/nm/km in a wavelength band of 1430 nm to 1625 nm, a dispersion slope in absolute value of 0.04 ps/nm2/km or less at a wavelength of 1550 nm, a mode field diameter of 7 ?m or less at a wavelength of 1550 nm and a cable cutoff wavelength of less than 1430 nm; core 11 surrounded by cladding 7, core 11 being at least two-layered (first layer 1 at the center and second layer 2 surrounding the first layer; relative refractive index of glass layer ?1 with reference to the cladding being adjusted to not less than 0.6 but not more than 1.6%, relative refractive index of second layer ?2 with reference to the cladding being adjusted to a negative value.

Abstract: Optical fibers to form an optical transmission line suitable for WDM transmission in a wide-spreading wavelength band, having the following characteristics and parameters: a dispersion in absolute value of 0.5 ps/nm/km to 9 ps/nm/km in a wavelength band of 1430 nm to 1625 nm, a dispersion slope in absolute value of 0.04 ps/nm2/km or less at a wavelength of 1550 nm, a mode field diameter of 7 ?m or less at a wavelength of 1550 nm and a cable cutoff wavelength of less than 1430nm; core 11 surrounded by cladding 7, core 11 being at least two-layered (first layer 1 at the center and second layer 2 surrounding the first layer; relative refractive index of glass layer ?1 with reference to the cladding being adjusted to not less than 0.6 but not more than 1.6%, relative refractive index of second layer ?2 with reference to the cladding being adjusted to a negative value.

Abstract: An inner core has a first refractive index. An outer core having a second refractive index lower than the first refractive index is formed on outer circumference of the inner core. A cladding having a refractive index that is higher than the second refractive index and lower than the first refractive index is formed on outer circumference of the outer core. A diameter of the inner core is enlarged, the second refractive index is decreased, and a center core having a refractive index lower than the first refractive index is formed at a center of the inner core, to increase an effective core area while maintaining wavelength dispersion and bending loss.

Abstract: Optical fibers to form an optical transmission line suitable for WDM transmission in a wide-spreading wavelength band, having the following characteristics and parameters: a dispersion in absolute value of 0.5 ps/nm/km to 9 ps/nm/km in a wavelength band of 1430 nm to 1625 nm, a dispersion slope in absolute value of 0.04 ps/nm2/km or less at a wavelength of 1550 nm, a mode field diameter of 7 ?m or less at a wavelength of 1550 nm and a cable cutoff wavelength of less than 1430 nm; core 11 surrounded by cladding 7, core 11 being at least two-layered (first layer 1 at the center and second layer 2 surrounding the first layer; relative refractive index of glass layer ?1 with reference to the cladding being adjusted to not less than 0.6 but not more than 1.6%, relative refractive index of second layer ?2 with reference to the cladding being adjusted to a negative value.

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 core and a cladding surrounding the core. An absolute value of dispersion at a wavelength of 1550 nanometers is equal to or more than 4 ps/nm/km and equal to or less than 10 ps/nm/km. An absolute value of dispersion slope at the wavelength of 1550 nanometers is equal to or less than 0.04 ps/nm2/km. An effective area at the wavelength of 1550 nanometers is equal to or more than 40 ?m2. A transmission loss at the wavelength of 1500 nanometers is equal to or less than 0.205 dB/km.

Abstract: Optical fibers to form an optical transmission line suitable for WDM transmission in a wide-spreading wavelength band, having the following characteristics and parameters: a dispersion in absolute value of 0.5 ps/nm/km to 9 ps/nm/km in a wavelength band of 1430 nm to 1625 nm, a dispersion slope in absolute value of 0.04 ps/nm2/km or less at a wavelength of 1550 nm, a mode field diameter of 7 ?m or less at a wavelength of 1550 nm and a cable cutoff wavelength of less than 1430 nm; core 11 surrounded by cladding 7, core 11 being at least two-layered (first layer 1 at the center and second layer 2 surrounding the first layer; relative refractive index of glass layer ?1 with reference to the cladding being adjusted to not less than 0.6 but not more than 1.6%, relative refractive index of second layer ?2 with reference to the cladding being adjusted to a negative value.

Abstract: An optical fiber includes a core and a cladding surrounding the core. An absolute value of dispersion at a wavelength of 1550 nanometers is equal to or more than 4 ps/nm/km and equal to or less than 10 ps/nm/km. An absolute value of dispersion slope at the wavelength of 1550 nanometers is equal to or less than 0.04 ps/nm2/km. An effective area at the wavelength of 1550 nanometers is equal to or more than 40 ?m2. A transmission loss at the wavelength of 1500 nanometers is equal to or less than 0.205 dB/km.

Abstract: Optical fibers to form an optical transmission line suitable for WDM transmission in a wide-spreading wavelength band, having the following characteristics and parameters: a dispersion in absolute value of 0.5 ps/nm/km to 9 ps/nm/km in a wavelength band of 1430 nm to 1625 nm, a dispersion slope in absolute value of 0.04 ps/nm2/km or less at a wavelength of 1550 nm, a mode field diameter of 7 ?m or less at a wavelength of 1550 nm and a cable cutoff wavelength of less than 1430 nm; core 11 surrounded by cladding 7, core 11 being at least two-layered (first layer 1 at the center and second layer 2 surrounding the first layer; relative refractive index of glass layer ?1 with reference to the cladding being adjusted to not less than 0.6 but not more than 1.6%, relative refractive index of second layer ?2 with reference to the cladding being adjusted to a negative value.

Abstract: An optical fiber has a zero dispersion wavelength in a wavelength range of 1350 to 1410 nanometers; a dispersion of 2 to 8 ps/nm/km at a wavelength of 1550 nanometers; a dispersion slope of a positive value and not more than 0.05 ps/nm2/km at a wavelength of 1550 nanometers; a transmission loss of not more than 0.4 dB/km at a wavelength of 1380 nanometers; an increase of transmission loss of not more than 0.04 dB/km at a wavelength of 1380 nanometers after a hydrogen aging test; a transmission loss of not more than 0.25 dB/km at a wavelength of 1550 nanometers; and a bending loss of not more than 30 dB/m when the optical fiber is wound at a diameter of 20 millimeters at a wavelength of 1550 nanometers.