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: An optical fiber is fabricated with a refractive index profile having a central core; a middle part provided around the outer periphery of the central core and having a lower refractive index than that of the central core; and a cladding provided around the periphery of the middle part and having a higher refractive index than the middle part and a lower refractive index than the central core. This optical fiber has an effective core area of 120 ?m2 or more in an employed wavelength band selected from the range of 1.53˜1.63 ?m, and has a cut-off wavelength that is capable of substantially single mode propagation in the aforementioned employed wavelength band. As a result, it is possible to construct an optical transmission system having excellent transmission characteristics in which nonlinearity is decreased.

Abstract: A polarization-maintaining optical fiber component which suppresses coupling of propagating light to a high-order mode at the optical coupling section of the polarization-maintaining optical fiber component, caused by different refractive indexes between the stress applying sections and the cladding, thus reducing excess loss, is constructed by using a polarization-maintaining optical fiber having stress applying sections arranged symmetrically to each other with respect to a core in a cladding surrounding the core, wherein the largest one of those concentric circles of the core or the said cladding which do not reach the stress applying sections and do not include the stress applying sections within has a diameter of 20 ?m or greater.

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 dispersion compensating optical fiber includes an uncovered dispersion compensating optical fiber containing a core and a cladding, and a resin coating which is disposed around the uncovered dispersion compensating optical fiber, wherein the resin coating has an adhesive property of 10 g/mm or less, and which includes an outer coating layer which is formed to have a thickness of 3 ?m or more, and the outer diameter of the uncovered dispersion compensating optical fiber is in a range from 90 to 125 ?m, and the outer diameter of the dispersion compensating optical fiber is in a range from 180 to 250 ?m.

Abstract: The present invention's multimode optical fiber is characterized in that the propagating modes include a mode the lowest and second or higher order modes; and the difference between the propagation constants of the lowest order mode and the second order mode is 2-fold or more than the difference between the propagation constants of adjacent modes that are second order or higher order modes. Due to this design, single mode propagation becomes possible once the modes have propagated over a specific distance. As a result, it is possible to relax the conventional single mode conditions, enabling the fiber parameters to be set relatively freely.

Abstract: This dispersion compensating optical fiber comprises an uncovered dispersion compensating optical fiber which contains a core and a cladding and a resin coating which is disposed around the uncovered dispersion compensating optical fiber and which has an adhesive property of 10 g/mm or less. Alternatively, the dispersion compensating optical fiber comprises an uncovered dispersion compensating optical fiber which contains a core and a cladding and a resin coating which is disposed around the uncovered dispersion compensating optical fiber, which has an adhesive property of 1 g/mm or less, and which includes a single or double coating layer and an outer coating layer formed on the surface of the single or double coating layer to have a thickness of 3 &mgr;m or more.

Abstract: In a method of manufacturing a polarization-maintaining optical fiber coupler by heating lengthwise portions of two polarization-maintaining optical fibers extending side by side, and elongating the heated portions to thereby form a fused-elongated section, elongation is terminated when the cyclic changes in a coupling ratio of two polarized waves according to an elongation length at a wavelength in use are both within first two cycles, so that the coupling ratio of one of the polarized waves is equal to or less than 10% and the coupling ratio of the other one of the polarized waves is equal to or greater than 90%. This method can provide a polarization-maintaining optical fiber coupler whose coupling ratio has a large dependency on polarization with a short elongation length.

Abstract: The present invention provides a multiple wavelength excitation light source characterized in the provision of an optical multiplexing element that has a plurality of input terminals connected to lasers and functions to multiplex a plurality of lights that have different characteristics; and a reflecting element inserted near the output side of the output terminal of the optical multiplexing element, and functioning to reflect the light multiplexed at the optical multiplexing element at a low reflection coefficient. Accordingly, it becomes possible to provide high output excitation light in a stable manner.

Abstract: An optical fiber grating is manufactured by heating intermittently an optical fiber, provided with a core having residual stress in the longitudinal direction, softening a peripheral cladding of the core, and forming spatial periodical changes for the relative refractive index-difference between the core and the cladding, in the longitudinal direction of the aforementioned optical fiber by having the index of refraction of the core change, through the releasing of the aforementioned residual stress. As a result, an optical fiber grating and the manufacturing method thereof, which do not require expensive equipment and which exhibit high productivity, and furthermore a grating characteristic which is stable over time can be provided.

Abstract: An optical fiber grating is manufactured by heating intermittently an optical fiber, provided with a core having residual stress in the longitudinal direction, softening a peripheral cladding of the core, and forming spatial periodical changes for the relative refractive index-difference between the core and the cladding, in the longitudinal direction of the aforementioned optical fiber by having the index of refraction of the core change, through the releasing of the aforementioned residual stress. As a result, an optical fiber grating and the manufacturing method thereof, which do not require expensive equipment and which exhibit high productivity, and furthermore a grating characteristic which is stable over time can be provided.

Abstract: An optical fiber grating is manufactured by heating intermittently an optical fiber, provided with a core having residual stress in the longitudinal direction, softening a peripheral cladding of the core, and forming spatial periodical changes for the relative refractive index-difference between the core and the cladding, in the longitudinal direction of the aforementioned optical fiber by having the index of refraction of the core change, through the releasing of the aforementioned residual stress. As a result, an optical fiber grating and the manufacturing method thereof, which do not require expensive equipment and which exhibit high productivity, and furthermore a grating characteristic which is stable over time can be provided.

Abstract: A method of producing an optical waveguide grating by exposure to light. An optical waveguide having a core composed of a material wherein the refractive index changes due to exposure to UV light is formed into an optical waveguide grating by applying a grating portion formation step wherein a grating portion is formed by irradiation with UV light at a predetermined spacing, and an overall exposure step after formation of the grating portion wherein the entire grating portion is irradiated with UV light. As a result, the effective refractive index of the grating portion is changed so as to allow the central wavelength to be adjusted without changing the rejection. Consequently, the grating properties can be precisely and easily controlled.

Abstract: The present invention is related to an dispersion compensating optical fiber technology, comprising a central core, a middle part with a refractive index lower than this central core, and a cladding with a refractive index higher than said middle part and lower than said central core, characterized in: an outer diameter of said middle part being 2.5.about.3.5 times an outer diameter of said central core; a relative refractive index difference of said cladding to said middle part being -0.08.about.-0.2% with the refractive index of the cladding being zero; and having substantially single-mode transmission in the wavelength 1.55 .mu.m band, the chromatic dispersion being -80 ps/nm/km or less, the dispersion slope being +0.08 ps/nm.sup.2 /km or less, and the bending loss being 1.0 dB/m or less.

Abstract: An optical waveguide grating with radiative mode-coupling properties, with exceptional stability and reliability as an optical component, wherein the central wavelength of the rejection band has a low temperature dependence, due to the use of silica glass doped with germanium and boron for the core. The rejection bandwidth can be narrowed without increasing the grating length by forming the radiative mode-coupled optical waveguide grating in an optical waveguide wherein the mean relative refractive index difference of the core is greater than that of optical communication waveguides.

Abstract: Core comprises a main stem which is formed on a substrate, linearly extending in the beam propagating direction and short branches with a certain length which extend perpendicularly to the beam propagating direction toward both sides along the plane of the substrate and are arranged at regular intervals in the beam propagating direction. Thus, the branches are arranged in a ladder geometry when it is viewed from the top, forming a rectangular waveform arrangement. The core constitutes a grating structure in which the width of the core is made to vary periodically with the branches in the beam propagating direction.

Abstract: In an optical-fiber coupler formed by disposing two single-mode optical fibers 1 and 2 in parallel, and fusing and elongating the optical fibers at one position in the longitudinal extent of the optical fibers 1 and 2, variation of insertion loss dependent on the polarization can be eliminated in its manufacturing by imparting a twist to the optical coupling part 3' of the fused-elongated portion 3 so that with respect to the direction of a line on a plane orthogonally intersecting the longitudinal direction of the optical fibers 1 and 2, the line linking the centers of the two optical fibers 1 and 2, the direction of the line on a plane at one end of the optical coupling part 3' of the fused-elongated portion 3 makes an angle of 90 degrees with the direction of the line on a plane at the other end of the optical coupling part 3'.

Abstract: The present invention relates to an optical fiber filter provided with a portion which selectively reflects or transmits light of a specific wavelength, this portion comprised of a multimode optical fiber in which the refractive index of the core changes periodically along the longitudinal direction thereof. Furthermore, this multimode optical fiber has an input end and an output end, with at least the input end of the multimode optical fiber being connected to a single mode optical fiber. As a result of forming an optical fiber filter in this way, it is possible to realize an optical fiber filter that exhibits no transmission loss at wavelengths other than the center wavelength.

Abstract: The polarization-maintaining optical fiber 10 of the present invention is designed so that a plurality of core portions 12a,12b which have a high refractive index is provided in parallel along a single diameter direction in the cross section of the optical fiber, these core portions 12a,12b cooperating to propagate a single fundamental mode. In the production method for the polarization-maintaining optical fiber of the present invention, a plurality of holes 22 are formed longitudinally in parallel along a single diameter direction of a glass rod 21 having a low refractive index which forms the cladding, glass rods 23 for core use having a high refractive index which form the core portions are inserted into these holes 22, heating to form a unitary body is carried out, creating a preform which is then drawn.

Abstract: A manufacturing method for erbium doped silica, having a soot formation process, in which a silica glass soot is deposited on a seed rod for forming a soot preform in a porous state on the seed rod, a dopant impregnation process, wherein the soot preform is impregnated with at least an erbium compound, and a preform formation process, wherein this soot preform impregnated with a dopant is heated and rendered transparent. The dopant impregnation process is provided with an operation in which the soot preform obtained in the soot formation process is dipped in a solution containing an erbium compound, an aluminum compound, and a phosphorus compound; this is then desiccated, and soot preform which is impregnated with the erbium compound, the aluminum compound, and the phosphorus compound is obtained.