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: There is disclosed an optical fiber wherein an absolute value of the fourth order dispersion ?4 of fourth derivative ?4 of propagation constant ? with respect to angular frequency ? at a mean zero dispersion wavelength ?0 in an overall length is not more than 5×10?56 s4/m and wherein a fluctuation of a zero dispersion wavelength along a longitudinal direction is not more than ±0.6 nm.

Abstract: This invention relates to an optical fiber and others having a structure for efficiently generating SC light while realizing high nonlinearity over a wide band. The optical fiber has at least a center core region, and an outside cladding region having a refractive index lower than that of the center core region and provided on an outer periphery of the center core region. The optical fiber has, as characteristics to light of a wavelength ?1 in a wavelength range of 1520 nm to 1620 nm, a chromatic dispersion of ?2 ps/nm/km to +2 ps/nm/km, a dispersion slope of ?0.009 ps/nm2/km to +0.009 ps/nm2/km, and a fourth-order dispersion of ?1.8×10?4 ps/nm3/km to +1.8×10?4 ps/nm3/km.

Abstract: Provided are a method of treating the inner surface of a silica tube, an optical fiber preform manufacturing method, and an optical fiber manufacturing method, in which the amount of discharge of a global warming gas is less than that in the case of a conventional method. The method of treating the inner surface of a silica tube comprises a step of heating the silica tube so as to have a temperature of 1800° C. or more while supplying a gas containing chlorine into the inside of the silica tube, thereby treating the inner surface of the silica tube with chlorine. The optical fiber preform manufacturing method further comprises a step of processing the silica tube into a rod. The optical fiber manufacturing method comprises a step of drawing an optical fiber preform prepared by the optical fiber preform manufacturing method.

Abstract: Provided is a method of manufacturing an optical fiber preform from which an optical fiber having the desired characteristics can easily be produced.

Abstract: Methods of manufacturing an optical fiber preform and an optical fiber, and an optical fiber formed by this method of manufacturing an optical fiber are provided, the optical fiber preform having a desired refractive index profile and being capable of suppressing an increase in loss due to the absorption by OH groups. A pipe is formed by an inside vapor phase deposition method such that glass layer to be formed into a core and a glass layer to be formed into a part of a cladding pipe are deposited in a starting pipe, the glass layers each containing at least one of fluorine, germanium, phosphorous, and chlorine, the starting pipe being made of a silica glass having an outside diameter in the range of 20 to 150 mm and a wall thickness in the range of 2 to 8 mm. The pipe thus formed is collapsed to form a glass rod in which the concentration of hydroxyl groups is 10 weight ppm or less in a region from the surface of the glass rod to a depth of 1 mm therefrom.

Abstract: An optical fiber preform comprises a central core portion having a maximal value Nc of refractive index in the center, and outside the central core portion, comprising at least a depressed portion having a minimal value Nd of refractive index, a ring portion having a maximal value Nr of refractive index and an outside cladding layer having a maximal value No of refractive index. The optical fiber preform satisfies a relation of Nc?Nr>No>Nd among the values of refractive index. A method of the optical fiber preform comprises fabricating a glass rod by inserting a rod containing at least the central core portion into a pipe containing at least the depressed portion and integrating them, fabricating a glass pipe having the ring portion, and fabricating a vitreous body by integrating the glass rod and the glass pipe by collapsing after inserting the glass rod into the glass pipe.

Abstract: A method for manufacturing an optical fiber preform that can produce an optical fiber having desired characteristics over the longer length thereof. A crude preform provided with a core region and a cladding region is prepared (Step S1), and at a plurality of positions in the longitudinal direction of the crude preform, a refractive index profile in the cross-section of the crude preform is measured (Step S2). Then, the shape of the cladding region is demarcated based on the shape of the profile (Step S3). Subsequently, the crude preform is ground based on the results of the demarcation (Step S4). Thus, an optical fiber preform that enables the manufacture of an optical fiber having target characteristics is manufactured.

Abstract: A method of manufacturing an optical fiber preform is provided, with which an increase of PMD and transmission loss of an optical fiber can be restrained. The method of manufacturing an optical fiber preform includes a process of heating a glass pipe and comprises the steps of (1) supporting the glass pipe at both ends thereof such that the longitudinal axis of the glass pipe becomes substantially horizontal and (2) heating the glass pipe with a heat source, wherein the bending moment at the supporting end of the glass pipe which is treated as a cantilever is 6 Nm or more, and the displacement of the heated region of the glass pipe in the heating process is equal to or less than 1.5 mm.

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. This invention provides a method for manufacturing an optical fiber 10 including forming a glass pipe 16 by applying a ring portion 15 on the inner face of a starting pipe 14 as a starting material, inserting a glass rod 13 that becomes a central core portion 11 and a depressed portion 12 into the inside of the glass pipe 16, integrating the glass pipe 16 and the glass rod 13 by collapse to form a glass body 17, forming a preform 10a by providing a jacket portion 18 outside the glass body 17, and drawing the preform 10a, wherein the thickness of the starting pipe 14 is set in a range from 4 mm to 8 mm.

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: An apparatus can heat a glass body with high efficiency, and a method incorporating the apparatus produces an optical fiber preform. The apparatus has (a) a heating element that has a nearly cylindrical shape and that heats a glass body inserted into the heating element and (b) an infrared reflector that is placed at a position next to each of the openings of the heating element, that surrounds the glass body together with the heating element, and that has an inner surface having a spectral emissivity of at most 0.70 in a wavelength range of 4 to 12 ?m.

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. The present invention involves a rod-in collapse process in which a glass rod is fixed within a glass pipe (or a dummy pipe attached to an end portion) via an aligning jig. The fixation via the aligning jig is made at one end or both ends, the aligning jig has a cylindrical shape with or without one or more reduced diameter portions. When fixed at one end, a heating and integrating process is preferably made from an opposite end. Employing the glass rod and the glass pipe having a refractive index distribution, a complex profile can be realized.

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: 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: In a glass processing method according to the invention, in the case of performing chemical vapor deposition or diameter shrinkage of a substrate glass tube G by relatively moving a heating furnace 20 comprising a heating element 21 for annularly enclosing the circumference of the substrate glass tube in a longitudinal direction of the substrate glass tube G with respect to the substrate glass tube G in which an outer diameter is 30 mm or more and a wall thickness is 3 mm or more and is less than 15 mm and an ovality of the outer diameter is 1.0% or less using a glass processing apparatus 1, a temperature of at least one of the heating element 21 and the substrate glass tube G is measured and the amount of heat generation of the heating element 21 is adjusted based on the measured temperature.

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/km1/2 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 ?m.

Abstract: The present invention relates to an optical transmission line and the like having a chromatic dispersion with a small absolute value as a whole within a signal wavelength band including S, C, and L bands. This optical transmission line comprises a single-mode optical fiber and a dispersion-compensating optical fiber which are connected to each other; and has, as characteristics of the whole optical transmission line at a wavelength of 1550 nm, a chromatic dispersion with an absolute value of 4 ps/nm/km or less, and a dispersion slope of ?0.015 ps/nm2/km or more but less than 0 ps/nm2/km. Its chromatic dispersion has a maximum value within a wavelength range of 1450 to 1530 nm, and a minimum value within a wavelength range of 1570 to 1620 nm.

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.