Abstract: The present invention, even in the case where the size of a preform itself is increased, enables production of a multi-core optical fiber in which cores are arranged with high accuracy. A plurality of core members each being rod-like are fixed by an array fixing member while a relative positional relation of the plurality of core members is fixed, and the plurality of core members and a cladding member are integrated into one piece, and thus a preform is obtained. By drawing the obtained preform, a multi-core optical fiber in which core arrangement is controlled with high accuracy is obtained.

Abstract: The present invention relates to an optical communications system that allows improving OSNR while suppressing the power increase of pumping light for distributed Raman amplification. In the optical communications system, an optical fiber is laid in a transmission section between a transmitter station (or repeater station) and a receiver station (or repeater station), and optical signals are transmitted from the transmitter station to the receiver station via the optical fiber. In the optical communications system, pumping light for Raman amplification, outputted by a pumping light source provided in the receiver station, is fed into the optical fiber via an optical coupler, and the optical signals are distributed-Raman-amplified in the optical fiber. The transmission loss and the effective area of the optical fiber satisfy, at the wavelength of 1550 nm, a predetermined relationship.

Abstract: The present invention relates to a measuring method and a sensor unit of measuring temperature distribution of an object by using an optical fiber sensing technology of BOCDA system. In the measuring method, an optical fiber that functions as a BOCDA-type optical fiber sensor is disposed two-dimensionally or three-dimensionally with respect to a predetermined measurement region of the object, and thereby the temperature distribution of the object can be measured at a high speed and a high accuracy, in the predetermined measurement region configuring a surface or space where the optical fiber is disposed.

Abstract: The present invention relates to an optical communication system or the like, which comprises a multicore fiber with a plurality of cores that are two-dimensionally arrayed in a cross-section thereof. In the optical communication system, an arrangement converter, provided between a multicore fiber and an Optical Line Terminal (OLT) having light emitting areas arrayed one-dimensionally, comprises first and second end faces, and a plurality of optical waveguides. The optical waveguides are disposed such that one of the end faces coincides with the first end face and the other end face coincides with the second end face. In particular, the optical waveguide end face array on the first end face and the optical waveguide end face array on the second face are different, contributing to an optical link between network resources of different types.

Abstract: The present invention relates to a measuring method and a controlling method of measuring the physical quantity such as a fluid temperature distribution and the like by using an optical fiber sensing technique of BOCDA system. In the measuring method, an optical fiber that functions as a BOCDA-type optical fiber sensor is disposed along a flow direction of a fluid that flows though a pipe line and in the pipe line. Since the optical fiber directly contacts with the fluid that flows though the pipe line, it is possible to rapidly measure the fluid temperature distribution. Also, based on this measurement result, the controlling method adjusts each temperature of one or more heating/cooling means provided along the longitudinal direction of a pipe line, thereby controlling at high accuracy the fluid temperature distribution in the pipe line.

Abstract: The present invention relates to a liquid conveying device and the like having a structure which liquid conveying can be performed to a sufficient height, while requiring no energy for liquid conveying and having a high degree of freedom of arrangement. The liquid conveying device 1 comprises a liquid conveying pipe 10, and a filter 20. The liquid conveying pipe 10 includes a minute tube having a through hole with a substantially uniform inner diameter over the whole longitudinal length thereof. The filter 20 has a mesh size smaller than the inner diameter of the through hole of the minute tube. When supplied to a first end of the liquid conveying pipe 10, a liquid passed through pores of the filter 20 is guided from the first end to a second end of the liquid conveying pipe 10 by a capillary action in the through hole.

Abstract: The present invention relates to an optical communications system that allows improving OSNR while suppressing the power increase of pumping light for distributed Raman amplification. In the optical communications system, an optical fiber is laid in a transmission section between a transmitter station (or repeater station) and a receiver station (or repeater station), and optical signals are transmitted from the transmitter station to the receiver station via the optical fiber. In the optical communications system, pumping light for Raman amplification, outputted by a pumping light source provided in the receiver station, is fed into the optical fiber via an optical coupler, and the optical signals are distributed-Raman-amplified in the optical fiber. The transmission loss and the effective area of the optical fiber satisfy, at the wavelength of 1550 nm, a predetermined relationship.

Abstract: The present invention relates to an optical cable with a structure for improving a durability performance. The optical cable comprises, as a basic structure: a coated optical fiber, and a cable jacket covering an outer periphery of the coated optical fiber. The coated optical fiber is constituted by a glass fiber and a coating layer of an ultraviolet curing resin. To realize excellent impact resistance as durability performance, the coating layer of the coated optical fiber includes a first coating with a Young's modulus of 200 MPa or more. Meanwhile, the cable jacket is comprised of a thermoplastic resin that does not contain any halogens. The cable jacket has a thickness of 0.7 mm or more, a flame retardancy of V2 or more according to UL Standards, and a Young's modulus equal to or greater than that of the first coating.

Abstract: The present invention relates to an optical communications system that allows improving OSNR while suppressing the power increase of pumping light for distributed Raman amplification. In the optical communications system, an optical fiber is laid in a transmission section between a transmitter station (or repeater station) and a receiver station (or repeater station), and optical signals are transmitted from the transmitter station to the receiver station via the optical fiber. In the optical communications system, pumping light for Raman amplification, outputted by a pumping light source provided in the receiver station, is fed into the optical fiber via an optical coupler, and the optical signals are distributed-Raman-amplified in the optical fiber. The transmission loss and the effective area of the optical fiber satisfy, at the wavelength of 1550 nm, a predetermined relationship.

Abstract: The present invention relates to a measuring method, etc., comprising a structure for accurately measuring optical characteristics such as PMD of an optical fiber. The measuring method is a technique for measuring polarization characteristic distributions along the longitudinal direction of the optical fiber as a measuring object by using BOCDA, and by propagating probe light and pumping light opposite in the optical fiber, BGS is generated at a plurality of respective measurement positions. Then, based on Brillouin gain fluctuations at the respective measurement positions, polarization characteristic distributions are calculated.

Abstract: The present invention relates to, for example, a method of easily manufacturing an optical fiber having any refractive index profile with fewer kinds of rods, and an optical fiber is manufactured by preparing a plurality of rods including at least two kinds of rods having different refractive indexes from each other, bundling rods selected from the plurality of rods to construct two or more rod units, producing a preform including a region in which the two or more rod units are combined so as to have a cross-sectional shape having rotational symmetry of order 2 or more, and manufacturing an optical fiber by drawing the preform.

Abstract: The present invention enables easy manufacturing of a thermal insulating fine fiber and the like, for example, having a high degree of freedom in size and shape and excellent thermal insulating properties. In a manufacturing method according to the present invention, a first end of a preform constituted by bundling a plurality of pipes 1 is sealed, and suction of inner gas of each of the pipes is carried out from a second end side of the preform. By heating the preform with the internal pressure of each of the pipes being thus reduced from the first end side and drawing the preform, a fine fiber is made from the preform. While drawing the preform, by intermittently providing the fine fiber with sealing portions for sealing holes in the fine fiber, a thermal insulating fine fiber is manufactured.

Abstract: The present invention provides an optical branching device and an optical communication system which are easy to connect with optical fibers. In the optical branching device, when light emitted from an optical fiber in a front stage is incident on an entrance port of a multicore optical fiber, the light propagates through a first core and then is distributed from the first core to four second cores by core-to-core crosstalk between the first and second cores. The light beams distributed to the four second cores propagate through the respective cores and are emitted to four optical waveguides optically coupled core-to-core thereto within a fan-out part at exit ports.

Abstract: The present invention relates to an optical fiber cable incorporating a multi-core fiber provided with a plurality of cores and a cladding region. The optical fiber cable has a jacket covering the multi-core fiber. The multi-core fiber is arranged so that a hold wrap holds the cores in a state in which they are provided with a bend of not more than a fixed radius of curvature, in order to reduce crosstalk between the cores.

Abstract: The present invention relates to a multi-core optical fiber having a structure for reducing transmission loss and nonlinearity. The multi-core optical fiber comprises plural cores extending along a center axis direction, and a cladding surrounding the peripheries of the plural cores. The cladding is comprised of silica glass doped with fluorine, and each of the plural cores is comprised of silica glass doped with chlorine or pure silica glass.

Abstract: The invention relates to a phase plate which is easy to manufacture such as to have a desirable characteristic and the like. The phase plate (10) is substantially shaped like a circular cylinder and has a fixed refractive index in a direction along a center axis (AX) of the circular cylinder. The phase plate (10) also has plural regions (11-18) sequentially arranged as concentric circles from the center in a cross section perpendicular to the center axis (AX). The boundary between two adjacent regions in the regions (11-18) can be distinguished by the difference between refractive indexes. Each of the regions (11, 13, 15, 17) has a refractive index n1, while each of the regions (12, 14, 16, 18) has a refractive index n2 (?n1).

Abstract: The present invention relates to a multicore optical fiber having a structure for effectively inhibiting polarization mode dispersion from increasing, and the multicore optical fiber comprises a plurality of multicore units and a cladding region integrally covering the plurality of multicore units while separating the multicore units from each other. Each of the plurality of multicore units includes a plurality of core regions arranged such as to construct a predetermined core arrangement structure on a cross section orthogonal to an axis. The core arrangement structure of each multicore unit on the cross section has such a rotational symmetry as to coincide with the unrotated core arrangement structure at least three times while rotating by 360° about a center of the multicore unit, thereby reducing the structural asymmetry of each multicore unit.

Abstract: The present invention relates to an optical fiber temperature sensor capable of reducing an error in a temperature measurement. The sensor comprises an optical fiber, an optical frequency difference adjusting section, a light source system, a spectrum measuring section, a temperature calculating section, and a correcting section. The light source system outputs, into different ends of the optical fiber, probe light and pumping light of which each center frequency is set corresponding to an instruction from the optical frequency difference indicating section respectively. The temperature calculating section calculates a temperature of an object based on BGS in a first domain measured by the spectrum measuring section. On the other hand, the correcting section outputs a correction instruction to the light source system so that BGS center frequency of a second domain may be in agreement with a reference value thereof.

Abstract: The present invention relates to an optical fiber distribution type detecting method and the like equipped with a structure for enabling efficient measurement of a temperature distribution or strain distribution. This method regulates a modulation frequency and modulation index for probe light and pumping light opposingly incident on an object from a light source and a phase difference between the probe light and pumping light, thereby successively setting the length and location of search domains in a region to be measured. In particular, a detection process is executed while resetting the search domain length shorter at a predetermined interval of time or when an abnormality is detected. Thus partly changing the distance resolution for a specific region in the course of the detection process enables efficient measurement operations in a short time.

Abstract: The present invention relates to an optical fiber characteristic distribution sensor comprising a structure to effectively reduce the measurement errors of position in the temperature distribution measurement etc. The sensor comprises an optical fiber section, part of which is installed in an object to be measured and to which probe light and pumping light are inputted in opposite directions. The optical fiber section includes a marker portion where data relating to the shape of a BGS in the maker has been preliminarily measured in a state where the optical fiber section is installed in a normal state. At the time of calculating the characteristic distribution in the longitudinal direction of the optical fiber section while measuring the data relating to the BGS shape, the errors of the calculated gain occurrence position are corrected, for example, by shifting the scanning range of phase difference between the probe light and the pumping light.