Abstract: A photoelectric conversion unit in which efficiency of optical coupling and stability of mechanical coupling improve is obtained. The photoelectric conversion unit includes a light density conversion element 11 which changes at an output end face the density of light that has impinged on an incident end face and outputs the light, and a photoelectric conversion element 13. The photoelectric conversion element 13 is arranged closely to a high light-density side of the light density conversion element 11, and integrated with this light density conversion element 11. The photoelectric conversion element 13 can be a solar cell or a light emission medium. In the light density conversion element 11, it is preferable that a refractive index profile in the radial direction in a section becomes a square distribution. Further, the light density conversion element 11 uses silica glass in a base member, and by changing the addition amount of impurity added in this glass, a refractive index profile is formed.

Abstract: The present invention relates to an optical waveguide manufacturing method, which excels in mass productivity of a planar optical waveguide. In an aggregating step, plural members (20), which have a rod (21) or pipe (22) shape respectively, are arranged and bundled so as to constitute a substantially similar figure to at least a part of a desired waveguide pattern on a cross-section perpendicular to the longitudinal direction of the members (20). The plural members (20) bundled in the aggregating step are, after being softened by heating, elongated in a longitudinal direction thereof in an elongating step, whereby an elongated body is formed. The elongated body formed in the elongating step is cut along a plane perpendicular to the longitudinal direction of the elongated body in a cutting step. By these steps, a planar optical waveguide, on which a waveguide pattern based on a micro-structure is formed, is manufactured.

Abstract: The present invention relates to a multi-core optical fiber having a structure to effectively reduce crosstalk between adjacent core regions among a plurality of core regions. The multi-core optical fiber (1) has a leakage reduction portion (50), at least a portion of which is arranged at a position on a straight line connecting adjacent core regions together among a plurality of core regions (10). The leakage reduction portion (50) reduces leakage light in the multi-core optical fiber (1) from each of the core regions (10), thereby effectively reducing crosstalk between adjacent core regions.

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 communications system equipped with a structure, capable of applying a PBGF as an optical transmission line, by which high capacity information transmission is enabled by use of the PBGF. The optical communications system (1) is provided with an optical transmitter (10), an optical receiver (20) and an optical transmission line (30). The optical transmitter (10) outputs signal light, whose phase or optical frequency is modulated, into the optical transmission line (30). The optical transmission line (30) transmits the signal light outputted from the optical transmitter (10) to the optical receiver (20). The optical receiver (20) receives the signal light transmitted from the optical transmitter (10) via the optical transmission line (30). The optical transmission line (30) includes a photonic band gap fiber having a hollow core.

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 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.

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 an optical fiber having a structure to enable both prevention of resin coating combustion due to leaked light, and low-loss light transmission. The optical fiber comprises a core region, and a cladding region. The cladding region is constituted by an optical cladding which affects the transmission characteristics of light propagating in the core region, and a physical cladding which does not affect the transmission characteristics of light propagating in the core region. Particularly, a leakage reduction portion is provided in the physical cladding so as to surround an outer periphery of the core region through the optical cladding. The leakage reduction portion functions to suppress propagation of the leaked light propagating from the core region toward outside the cladding region.

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 a dispersion compensating module having a configuration that can effectively suppress high-speed fluctuations in the polarization state of light even when being imparted with impact or vibration. In the dispersion compensating module, a dispersion compensating optical fiber is fixed while being wound around the barrel of a bobbin, and the bobbin is fixed in the inside of a housing via a buffer that absorbs impact or vibration. The bobbin corresponds to a holder holding the dispersion compensating optical fiber fixed in a state of coil. The housing corresponds to a struct fixing the holder. The buffer fills a space between the housing and the bobbin on which the dispersion compensating optical fiber is coiled.

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 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 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: This invention relates to optical sensing technology to measure and control a physical quantity of an object that exists on or within a microstructure object, utilizing Brillouin scattering decreases. The measurement method prepares an optical waveguide one-, two- or three-dimensionally, on or within a micro-chemical chip, IC chip, or other element, and measures a physical quantity of the object on the basis of a property variation of light attributed to Brillouin scattering occurring in the optical waveguide.

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 sensor or the like having a structure that enables accurate temperature measurement in a wide temperature range including a low-temperature region and is suitable for independently and accurately determining temperature variations and strains appearing in an object to be measured. The sensor comprises a laser light source, a sensor section that has a plurality of waveguides transmitting a laser light from the laser light source therethrough, a detecting section, and an analyzing section. The detecting section detects a plurality of Brillouin spectra obtained from the sensor section. The analyzing section determines at least one measurement value of a temperature in the sensor section and a strain generated in the sensor section, based on fluctuations of parameters defining the respective detected Brillouin spectra. In particular, the sensor section has a structure such that the variation of the Brillouin spectrum in response to a disturbance differs between the waveguides.

Abstract: The temperature measuring device of the present invention comprises: a light source for outputting light; an optical fiber to which light outputted by the light source is inputted and from which Brillouin scattered light is outputted; a detection unit for detecting a spectrum of the Brillouin scattered light; a judgment unit for judging whether or not a frequency shift of the spectrum of the Brillouin scattered light detected by the detection unit belongs to a specific region in which the rate of change of the frequency shift with respect to the temperature of the optical fiber is smaller than a predetermined value; and an analysis unit for, when the judgment unit judges that the frequency shift does not belong to the specific region, analyzing the temperature in use of the frequency shift, and for, when the judgment unit judges that the frequency shift belongs to the specific region, not performing analysis, or analyzing the temperature in use of at least the linewidth of the spectrum of the Brillouin scatte

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: The temperature measuring device of the present invention comprises: a light source for outputting light; an optical fiber to which light outputted by the light source is inputted and from which Brillouin scattered light is outputted; a detection unit for detecting a spectrum of the Brillouin scattered light; a judgment unit for judging whether or not a frequency shift of the spectrum of the Brillouin scattered light detected by the detection unit belongs to a specific region in which the rate of change of the frequency shift with respect to the temperature of the optical fiber is smaller than a predetermined value; and an analysis unit for, when the judgment unit judges that the frequency shift does not belong to the specific region, analyzing the temperature in use of the frequency shift, and for, when the judgment unit judges that the frequency shift belongs to the specific region, not performing analysis, or analyzing the temperature in use of at least the linewidth of the spectrum of the Brillouin scatte