Abstract: To provide a manufacturing method for an optical fiber preform and a manufacturing method for an optical fiber in which the optical fiber with a complex profile is produced at high precision, and an optical fiber.

Abstract: Stress exerted on an inner or outer circumferential side of a glass tube 6 is controlled when a glass material 3 is heated and softened by a heating element 41 provided around the glass material 3 and a piercing plug 31 is relatively pressed into a softened region of the glass material 3 to thereby form the glass material 3 into the glass tube 6 gradually. For example, the control of the stress can be carried out by controlling an internal or external pressure of the glass tube 6. As a result, the deformation of the glass tube 6 just after piercing is prevented so that the glass tube 6 can be obtained with high quality. It is also possible to solve the problem that cracks may occur easily at the time of reheating because of residual stress distribution after cooling.

Abstract: The present invention relates to a wavelength converter of structure enabling generation of converted light with high power even with a large difference between the wavelength of pumping light and the zero-dispersion wavelength. The wavelength converter includes an optical fiber having a dispersion slope whose absolute value at the wavelength of 1550 nm is 0.01 ps/nm2/km or less, for example.

Abstract: An optical transmission path in a Raman gain module (1) for transmitting signal light input from an input terminal (1a) and Raman-amplifying the signal light by pumping light supplied from pumping light source units (21, 22) is formed by connecting in series two Raman amplification optical fibers (11, 12) having different wavelength dispersion values. According to this arrangement, wavelength dispersion in the amplifier module (1) can be controlled using, e.g., the combination of the wavelength dispersion values of the Raman amplification optical fibers (11, 12). Hence, accumulation of dispersion into signal light and signal light transmission in an almost zero dispersion state are prevented, and degradation in signal light transmission quality due to the nonlinear optical effect is suppressed.

Abstract: A glass-processing method adjusts the range of the heating region according to the work piece and processing condition, and a glass-processing apparatus implements the method. The method incorporates the heating of a glass body with a thermal plasma torch comprising (a) a main body provided with a plurality of ports from which a gas issues and (b) a device for applying a high-frequency electric field to the gas fed into the main body. The method comprises the steps of (1) adjusting the plasma flame's size perpendicular to the center axis of the main body by controlling the flow rate of the gas fed into each port according to the size of the glass body, the processing condition, or both and (2) heating the glass body.

Abstract: An object of the present invention is to provide an optical fiber manufacturing method and an optical fiber in which an increase in the transmission loss is suppressed by preventing hydroxyl group from entering near the core portion.

Abstract: Proposed are a dispersion compensating fiber and an optical transmission system that can, using a short length of the fiber, compensate the chromatic dispersion and the dispersion slope of a non-zero dispersion shifted fiber whose chromatic dispersion is +2 ps·nm−1·km−1 to +10 ps·nm−1·km−1 and whose dispersion slope is +0.04 ps·nm−2·km−1 to +0.12 ps·nm−2·km−1 at 1550 nm. In the optical transmission system 1, an optical transmission line 30 that consists of a dispersion-shifted fiber 31 and a dispersion compensation fiber 32 is installed between stations 10 and 20. The dispersion compensating fiber 32 has the chromatic dispersion of −250 ps·nm−1·km−1˜−40 ps·nm−1·km−1 and the dispersion slope of 0.015 ps·nm−2·km−1˜0.030 ps·nm−2·km−1 at 1550 nm.

Abstract: A Raman amplifier is structured for resistance to signal waveform deterioration and excellent transmission quality. A wavelength spacing is arranged so that non-degenerate type four-wave mixing is effectively suppressed. When the Raman amplification optical waveguide has a positive dispersion slope with respect to the signal light, the zero-dispersion wavelength &lgr;0 of the Raman amplification optical waveguide is shorter than the center wavelength &lgr;center. When the Raman amplification optical waveguide has a negative dispersion slope with respect to the signal light, the zero-dispersion wavelength &lgr;0 of the Raman amplification optical waveguide is longer than the center wavelength &lgr;center.

Abstract: A method of producing with the collapsing process an optical fiber preform capable of forming an optical fiber in which an increment in transmission loss due to OH absorption is reduced, and an optical fiber preform and an optical fiber produced with the method. The method comprises reducing the amount of hydrogen atom-containing substances in a glass pipe, sealing one end of the glass pipe, and collapsing the glass pipe to obtain a solid body. One aspect of the method comprises heating the glass pipe at 550° C. or below, sealing one end of the glass pipe, and collapsing the glass pipe to obtain a solid body. The preform produced with the method has a feature in that its portion formed by the interface portion at the time of the collapsing contains OH groups at a concentration of 100 wt. ppb or below. The optical fiber produced by drawing the preform has a feature in that its OH-originated loss is less than 0.5 dB/km at a wavelength of 1.38 &mgr;m.

Abstract: The present invention relates to a method of making a glass tube. In the method, a diameter expanding member is inserted through a hole in a tubular glass blank so as to expand the diameter of the hole while the temperature of the glass blank is controlled to be more than or equal to the softening point. The tubular glass blank may be a purchased product or a self-made product. In the above-mentioned method of making a glass tube, the diameter of the hole in the glass blank may be expanded while at least the rear end of the diameter expanding member is supported. The diameter of the hole in the glass blank may be expanded while both ends of the diameter-expanding member are supported. The present invention also relates to an apparatus for manufacturing a glass tube.

Abstract: An optical fiber is composed of silica glass and comprises a center core region doped with F element, a ring core region doped with GeO2, and an inner cladding region doped with F element; wherein a buffer layer composed of undoped SiO2 or SiO2 doped with one or both of P and Cl or a concentration gradient region in which GeO2 concentration radially decreases toward the boundary is provided between the center core region and the ring core region.

Abstract: This application relates to a piperazino-substituted novel cyanophenyl derivative in which a substituted carbamoyl or substituted sulfamoyl group having an aryl, heterocyclic or the like group that may have a substituent group is bonded to one nitrogen atom on the piperazine ring. The compound of this application has an anti-androgen action and is useful in preventing or treating prostatic cancer, benign prostatic hyperplasia and the like diseases.

Abstract: There is disclosed a dispersion-compensating optical fiber exhibiting, at a wavelength of 1500 nm, a chromatic dispersion of −30 ps/nm/km or less, a ratio (S/D) of −0.08/nm to +0.05/nm between chromatic dispersion D and dispersion slope S, a polarization mode dispersion of 0.3 ps/kml/1/2 or less, and a transmission loss of 1 dB/km or less, and an excess loss of 0.2 dB/km or less due to OH group in a wavelength band of 1.4 &mgr;m.

Abstract: This application relates to a piperazino-substituted novel cyanophenyl derivative in which a substituted carbamoyl or substituted sulfamoyl group having an aryl, heterocyclic or the like group that may have a substituent group is bonded to one nitrogen atom on the piperazine ring. The compound of this application has an anti-androgen action and is useful in preventing or treating prostatic cancer, benign prostatic hyperplasia and the like diseases.

Abstract: Employed as a structure of a highly nonlinear optical fiber (nonlinear optical fiber) is a double-cladding structure in which a first cladding region 20 and a second cladding region 30 are disposed on the outer periphery of a core region 10. Since the double-cladding structure is employed, the cutoff wavelength &lgr;c can sufficiently be shortened even when, in order to increase the nonlinear coefficient &ggr;, the concentration of GeO2 added into the core is enhanced so as to raise the nonlinear refractive index, or the relative refractive index difference between the core and cladding is increased so as to reduce the effective area Aeff. This realizes an optical fiber or nonlinear optical fiber shortening its cutoff wavelength while having a sufficient nonlinearity, an optical amplifier and wavelength converter using the same, and a method of making an optical fiber.

Abstract: The present invention relates to an optical fiber having a structure suitable for long-distance optical communications, and an optical transmission line including the same. The optical fiber in accordance with the present invention comprises a core region extending along a predetermined axis, and a cladding region disposed so as to surround the outer periphery of the core region; and, as characteristics at a wavelength of 1.55 &mgr;m, an effective area of at least 110 &mgr;m2, a dispersion of 18 to 23 ps/nm/km, and a dispersion slope of 0.058 to 0.066 ps/nm2/km.

Abstract: Provided is a pharmaceutical composition containing a propane-1,3-dione derivative as the active ingredient, particularly a GnRH receptor antagonist. Also, provided is a propane-1,3-dione derivative having a GnRH antagonistic effect.

Abstract: An optical fiber is composed of silica glass and comprises a center core region doped with F element, a ring core region doped with GeO2, and an inner cladding region doped with F element; wherein a buffer layer composed of undoped SiO2 or SiO2 doped with one or both of P and Cl or a concentration gradient region in which GeO2 concentration radially decreases toward the boundary is provided between the center core region and the ring core region.

Abstract: An optical fiber preform having a low core noncircularity and eccentricity for producing an optical fiber having an improved polarization mode dispersion, a method for producing the preform, and an optical fiber produced from the preform. The optical fiber preform is produced by the following steps. Diameter-reduced portions 11a and 11b are formed in the vicinity of the ends of the glass pipe 11. A glass rod 12 is inserted into the glass pipe 11. The glass rod 12 is fixed to the glass pipe 11 at the diameter-reduced portion 11a. The glass pipe 11 and the glass rod 12 are heat-unified from the diameter-reduced portion 11b forward to the diameter-reduced portion 11a. The optical fiber preform has a core noncircularity of at most 1.5%. The optical fiber has a polarization mode dispersion of at most 0.15 ps/km1/2 at a wavelength of 1,550 nm.

Abstract: An object of the present invention is to provide a method for manufacturing an optical fiber preform having a great diameter by reducing an eccentricity or a non-circularity of a core, an optical fiber preform having an small non-circularity and a complex refractive index profile, even with a great diameter, and an optical fiber that is applicable as a dispersion compensating fiber.