Abstract: The present invention provides an optical fiber enabling signal transmission in a wider band, which is applicable to optical transmission not only in the 1.3 ?m wavelength band but also in the 1.55 ?m wavelength band, as a transmission medium of a WDM optical communication system capable of transmitting signal light of multiple channels. The optical fiber is comprised of silica glass and has a core region along a predetermined axis and a cladding region provided on the outer periphery of the core region. The optical fiber comprising such a structure has, as the following typical optical characteristics, a cable cutoff wavelength of 1260 nm or less, a transmission loss of 0.32 dB/km or less at the wavelength of 1310 nm, and an OH-related loss increase of 0.3 dB/km or less at the wavelength of 1380 nm.

Abstract: The present invention relates to a method of forming a transmission line capable of measuring more precise connection losses at low cost, and so on. At least of first and second optical fibers to be connected as components of the optical transmission line is selected such that, at one wavelength ? contained in the wavelength range of 1260 nm to 1625 nm, predetermined relationships defined by the Rayleigh scattering coefficients of the first and second optical fibers, the mode field diameters of the first and second optical fibers at the wavelength ?, and the transmission losses of the first and second optical fibers at the wavelength ? can be satisfied between the first and second optical fibers.

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: A DGD compensating apparatus capable of compensating the time varying DGD of each wavelength component in the propagation light. The DGD of each wavelength component in the inputted light is monitored by a DGD monitor, and a polarization splitter splits the inputted light into first polarization light and second polarization light orthogonal to each other. The first polarization light is de-multiplexed by de-multiplexer for each wavelength component, and the de-multiplexed wavelength components in the first polarization light are multiplexed by a multiplexer after being respectively added with delays by an optical delay. The first polarization light in which each wavelength component is added with the associated delay and the second polarization light are combined and thereafter being outputted by a polarization combiner.

Abstract: An optical cable according to the present invention relates to an optical cable having a construction to enable reduction of a cable outer diameter, and/or improvement of contained efficiency of coated optical fibers while an increase of transmission loss in each coated optical fiber is suppressed. The optical cable has a loose-tube type of structure constructed by: a tension member; a plurality of tubes stranded together around the tension member; and an outer sheath covering the outer periphery of the plurality of tubes. One or more coated optical fibers are contained in each tube. A ratio of A/B is 6.3 or more but 7.0 or less, where each coated optical fiber has a mode field diameter A in a range of 8.6±0.4 ?m at a wavelength of 1.31 ?m, and where a fiber cutoff wavelength thereof is B ?m.

Abstract: In the dispersion-compensating system of the present invention, a demultiplexer demultiplexes optical signals in a signal wavelength band of 1520 nm to 1620 nm propagating through a first common transmission line into C band (1520 nm to 1565 nm) and L band (1565 nm to 1620 nm). Then, the demultiplexer outputs the optical signals of C band into a first branched transmission line and the optical signals of L band into a second branched transmission line. A first dispersion-compensating device is provided on the first common transmission line and compensates for the dispersion in C and L bands. A second dispersion-compensating device is provided on the second branched transmission line and compensates for the dispersion in L band, which has not fully been compensated for by the first dispersion-compensating device. Hence, the dispersion of optical transmission line can fully be reduced in a wide signal light wavelength band.

Abstract: An optical cable according to the present invention relates to an optical cable having a construction to enable reduction of a cable outer diameter, and/or improvement of contained efficiency of coated optical fibers while an increase of transmission loss in each coated optical fiber is suppressed. The optical cable has a loose-tube type of structure constructed by: a tension member; a plurality of tubes stranded together around the tension member; and an outer sheath covering the outer periphery of the plurality of tubes. One or more coated optical fibers are contained in each tube. A ratio of A/B is 6.3 or more but 7.0 or less, where each coated optical fiber has a mode field diameter A in a range of 8.6±0.4 ?m at a wavelength of 1.31 ?m, and where a fiber cutoff wavelength thereof is B ?m.

Abstract: The present invention provides a chromatic-dispersion measuring apparatus and method that can quickly measure chromatic dispersion in an optical fiber even when the optical fiber is short. Continuous light beams having the wavelengths ?1 and ?2 output from light sources are multiplexed by a multiplexer, are intensity-modulated by an intensity modulator, and are then output as optical signals. The output optical signals with the wavelengths ?1 and ?2 enter an optical fiber to be measured, and propagate therethrough. The optical signals emerging from the optical fiber are de-multiplexed by a de-multiplexer, and are received by corresponding photodetectors. Subsequently, the phase difference between the optical signals received by the photodetectors is detected by a phase detector. The chromatic dispersion of the optical fiber is calculated by an arithmetical circuitry on the basis of the detection result.

Abstract: A dispersion compensating optical fiber comprises a minimum wavelength at which an increase amount of an actual loss value with respect to a theoretical loss value is not less than 10 mdB/km in a use wavelength band and on a long wavelength side of the use wavelength band. The actual loss value is measured in a state that the fiber is looped around a bobbin. The minimum wavelength falls within a range of 1,565 to 1,700 nm. This dispersion compensating optical fiber is suitably used for an optical transmission line of a large-capacity high-speed WDM optical transmission system.

Abstract: Provided is an optical transmission line in which the suppression of SBS and the achievement of other transmission characteristics can compatibly be attained. The optical transmission line is formed by connecting a first optical fiber and a second optical fiber, or by connecting a group of first optical fibers and a group of second optical fibers, in which the difference in Brillouin frequency shift therebetween is 200 MHz or more. In at least one of the first optical fiber and the second optical fiber, the transmission loss may be 0.32 dB/km or less at a wavelength of 1383 nm. In each of the first and second optical fibers, the mode field diameter may be not less than 8.2 ?m and not more than 9.8 ?m, the cable cutoff wavelength may be equal to or less than 1260 nm, and the zero dispersion wavelength may be not less than 1300 nm and not more than 1324 nm.

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: The present invention provides an optical transmission system and so on having a structure that enables to reduce variations between wavelengths in chromatic dispersion over a wide wavelength range and control non-linear optical effects. An optical fiber transmission line comprises a first optical fiber having a positive chromatic dispersion such that its wavelength dependence is reduced over a wide wavelength range, and a second optical fiber having a negative chromatic dispersion such that its wavelength dependence is reduced over the wavelength range. In this way, the first and second optical fibers each have a chromatic dispersion of a different polarity, thereby controlling accumulated chromatic dispersions at low level for a whole optical fiber transmission line, while the chromatic dispersion occurs to some extent in each of the first and second optical fibers, thereby controlling effectively non-linear optical effects such as four-wave mixing.

Abstract: In the dispersion-compensating system of the present invention, a demultiplexer demultiplexes optical signals in a signal wavelength band of 1520 nm to 1620 nm propagating through a first common transmission line into C band (1520 nm to 1565 nm) and L band (1565 nm to 1620 nm). Then, the demultiplexer outputs the optical signals of C band into a first branched transmission line and the optical signals of L band into a second branched transmission line. A first dispersion-compensating device is provided on the first common transmission line and compensates for the dispersion in C and L bands. A second dispersion-compensating device is provided on the second branched transmission line and compensates for the dispersion in L band, which has not fully been compensated for by the first dispersion-compensating device. Hence, the dispersion of optical transmission line can fully be reduced in a wide signal light wavelength band.

Abstract: Provided is an optical transmission line in which the suppression of SBS and the achievement of other transmission characteristics can compatibly be attained. The optical transmission line is formed by connecting a first optical fiber and a second optical fiber, or by connecting a group of first optical fibers and a group of second optical fibers, in which the difference in Brillouin frequency shift therebetween is 200 MHz or more. In at least one of the first optical fiber and the second optical fiber, the transmission loss may be 0.32 dB/km or less at a wavelength of 1383 nm. In each of the first and second optical fibers, the mode field diameter may be not less than 8.2 ?m and not more than 9.8 ?m, the cable cutoff wavelength may be equal to or less than 1260 nm, and the zero dispersion wavelength may be not less than 1300 nm and not more than 1324 nm.

Abstract: In the dispersion-compensating system of the present invention, a demultiplexer demultiplexes optical signals in a signal wavelength band of 1520 nm to 1620 nm propagating through a first common transmission line into C band (1520 nm to 1565 nm) and L band (1565 nm to 1620 nm). Then, the demultiplexer outputs the optical signals of C band into a first branched transmission line and the optical signals of L band into a second branched transmission line. A first dispersion-compensating device is provided on the first common transmission line and compensates for the dispersion in C and L bands. A second dispersion-compensating device is provided on the second branched transmission line and compensates for the dispersion in L band, which has not fully been compensated for by the first dispersion-compensating device. Hence, the dispersion of optical transmission line can fully be reduced in a wide signal light wavelength band.

Abstract: The present invention relates to an optical fiber or the like which allows more precise compensation for the chromatic dispersion of a transmission optical fiber over a broad wavelength band. The optical fiber has a chromatic dispersion of ?100 ps/nm/km or less in a wavelength band of 1535 to 1565 nm, 1565 to 1610 nm, 1554 to 1608 nm or 1535 to 1610 nm. In particular, the chromatic dispersion profile of the fundamental mode of this optical fiber defined by the orthogonal coordinate system of the wavelength and chromatic dispersion value has a shape such that, over the entire wavelength band except for the shortest and longest wavelengths thereof, the chromatic dispersion values on the chromatic dispersion profile are respectively located on the minus side of the associated chromatic dispersion values on a straight line connecting the chromatic dispersion values at the shortest and longest wavelength.

Abstract: The present invention relates to an optical fiber and the like comprising a structure enabling high-density packaging into an optical cable while making it possible to transmit signals with a high bit rate in both of wavelength bands of 1.3 ?m and 1.55 ?m. For example, this optical fiber is configured so as to have a mode field diameter of 8.0 ?m or less at a wavelength of 1.55 ?m, a cutoff wavelength of 1.26 ?m or less, and a chromatic dispersion with an absolute value of 12 ps/nm/km or less at wavelengths of 1.3 ?m and 1.55 ?m, thereby yielding an excellent lateral pressure resistance enabling high-density packaging into an optical cable.

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: After a wide-band DCF is wound around a bobbin to form an optical fiber coil 32, the latter is removed from the bobbin and placed into a bundle state (the state where the increase in transmission loss in the wavelength band of 1.55 ?m caused by distortions in winding is reduced by 0.1 dB/km or more) released from distortions in winding. A resin 42 is used as a coil-tidying member so as to secure the optical fiber coil 32 to a storage case 40 at four positions. Both ends of the optical fiber coil 32 are connected to pigtail fibers at fusion-splicing parts 44, respectively. Even when the storage case 40 is closed with a lid after the optical fiber coil 32 is secured to the storage case 40 with the resin 42, there remain interstices within the bundle of the optical fiber coil 32 and a space between the optical fiber coil 32 and the storage case 40. As a result, even when the optical fiber coil 32 in a bundle state is accommodated in the storage case 40, transmission loss and the like would not increase.

Abstract: The present invention provides an optical fiber enabling signal transmission in a wider band, which is applicable to optical transmission not only in the 1.3 ?m wavelength band but also in the 1.55 ?m wavelength band, as a transmission medium of a WDM optical communication system capable of transmitting signal light of multiple channels. The optical fiber is comprised of silica glass and has a core region along a predetermined axis and a cladding region provided on the outer periphery of the core region. The optical fiber comprising such a structure has, as the following typical optical characteristics, a cable cutoff wavelength of 1260 nm or less, a transmission loss of 0.32 dB/km or less at the wavelength of 1310 nm, and an OH-related loss increase of 0.3 dB/km or less at the wavelength of 1380 nm.