Abstract: The invention is directed to a silver-containing polarizing boroaluminosilicate glass composition that has been doped with a noble metal selected from the group consisting of Pt, Pd, Os, Ir, Rh and Ru, including mixtures thereof, to nucleate and precipitate silver ions to silver metal without the need for a reducing atmosphere step. The invention is further directed to a method for making the glass composition of the invention. Using the composition and method of the invention, one can prepare a glass having a selected null transmission range.

Abstract: An electric furnace extending method and apparatus for an optical fiber glass body alignment when connecting the extension use body and pulling member and making it possible to immediately start the extension after the fusing of the connection portion. A centering mechanism for centering the free end portion of the body and member on the furnace center side is provided between the furnace pipe of the electric furnace and grips of the extension use glass body and between the furnace pipe and the pulling member. The free end portion is centered by this centering mechanism, then the gripped sides of the body and member are fixed, the front ends of the two free end portions are abutted and fused and bonded at the highest temperature portion inside the electric furnace, then the highest temperature portion is moved to the extension portion of the glass body side and the extending of the glass body is commenced.

Abstract: Disclosed is a heating element having a ring shape provided in a furnace for drawing an optical fiber from a large-diameter preform so as to heat and melt a preform. The heating element according to heating element includes at least two hot zones having different heating temperatures, wherein one of the hot zones is arranged in a neck-down region of the preform to heat the preform at a temperature suitable for drawing an optical fiber. Also, the hot zone includes a first heating unit for heating a preform at a temperature suitable for draw an optical fiber from the preform; and a second heating unit for heating a surface of the preform to a relatively lower temperature than the first heating unit.

Abstract: In a known method for producing a cylindrical glass body in a vertical drawing process, a glass blank is softened in a heating zone and drawn off as a glass strand by means of a draw-off device at a controlled drawing speed, the draw-off device comprising a first draw-off unit with rolling bodies rolling on the glass strand and being distributed around the circumference thereof, the rolling bodies being formed by a reference rolling body and at least one auxiliary rolling body, the drawing speed being controlled via the speed of the reference rolling body.

Abstract: Optical fiber manufacturing methods, which manufacture optical fibers with uniform characteristics using a simple device construction, are provided. The optical fiber manufacturing methods comprise, drawing a glass fiber from a glass preform by heating and melting one end of the glass preform and coating at least one layer of resin around the circumference of the drawn glass fiber. The method includes the steps of decreasing the viscosity of the resin from an initial viscosity during a start-up process time to a steady viscosity as optical fiber draw speed increases, wherein the steady viscosity is a predetermined viscosity; and increasing the draw speed during the start-up process time to a faster steady speed.

Abstract: Drawing methods and drawing furnaces for drawing an optical fiber with small non-circularity by simple drawing system are provided. An optical fiber preform is received into a muffle tube and heated by a primary heater placed to surround the muffle tube. The optical fiber preform is heated such that a starting position of a meniscus portion is higher in its position than the top of the primary heater, wherein the meniscus portion is created at the bottom portion of the optical fiber preform.

Abstract: Optical devices and a method for manufacturing these devices. One optical device includes a core region having a first medium of a first refractive index n1, and includes a cladding region exterior to the core region. The cladding region includes a second medium having a second refractive index n2 higher than the first refractive index n1. The cladding region further includes a third medium having a third refractive index n3 lower than the first refractive index n1. The third medium is dispersed in the second medium to form a plurality of microstructures in the cladding region. Another optical device includes a plurality of core regions including at least one core having a doped first medium, and includes a cladding region exterior to the plurality of core regions. The core regions and the cladding region include a phosphate glass.

Abstract: A method of fabricating micro/nano optical wires is disclosed, which comprises: providing a micro/nano optical wire drawing device comprising a feeding wheel, a drawing wheel, and a heating unit; fastening one end of a micrometer-sized preform at the feeding wheel; making the other end of the preform pass through the heating unit and be fastened at the drawing wheel; and switching on the heating unit to heat the perform to a softening temperature of the preform and drawing the preform by the drawing wheel to form a micro/nano optical wire. A device of fabricating micro/nano optical wires is also disclosed.

Abstract: The glass fiber for an optical amplifier has a glass core, a first glass cladding, and a second glass cladding. The core has a composition, in mol %, of Bi2O3, 30-60; SiO2, 0.5-40; B2O3, 0.5-40; Al2O3, 0-30; Ga2O3, 0-20; Ge2O3, 0-25; La2O3, 0-15; Nb2O5, 0-10; SnO2, 0-30; alkali metal oxides, 0-40; and Er2O3, 0.05-8. The process for making the glass fiber includes first making a preform consisting of the core and the first glass cladding by drawing from a double crucible. Then the second glass cladding is formed around the preform by a rod-in-tube process. The glass claddings have a composition that includes a transition metal compound as an absorbent.

Abstract: A method for producing an optical fiber that includes a method for producing an optical fiber, said method comprising: (i) drawing a bare optical fiber from a preform along a first pathway at a rate of at least 10 m/sec; (ii) contacting said bare optical fiber with a region of fluid in a fluid bearing and redirecting said bare optical fiber along a second pathway as said bare optical fiber is drawn across said region of fluid cushion; (iii) coating the bare optical fiber; and (iv) irradiating said coated fiber in at least one irradiation zone to at least partially cure said coating, while subjecting the optical fiber to UV light.

Abstract: An expeditious method for introducing geometric perturbations into lightguide during fabrication offers a perturbation stream of amplitude and periodicity—constant or varying—to satisfy a variety of needs.

Abstract: A random array of holes is created in an optical fiber by gas generated during fiber drawing. The gas forms bubbles which are drawn into long, microscopic holes. The gas is created by a gas generating material such as silicon nitride. Silicon nitride oxidizes to produce nitrogen oxides when heated. The gas generating material can alternatively be silicon carbide or other nitrides or carbides. The random holes can provide cladding for optical confinement when located around a fiber core. The random holes can also be present in the fiber core. The fibers can be made of silica. The present random hole fibers are particularly useful as pressure sensors since they experience a large wavelength dependant increase in optical loss when pressure or force is applied.

Abstract: When forming a taper portion on an end of a glass base material for manufacturing an optical fiber, the taper portion is formed by fusing the glass base material from a modified point after modifying a center-line displacement amount of a fusing point for a center line of the glass base material to a value not more than a predetermined numeric value. Moreover, in a glass base material for drawing having an effective straight base with an average outside diameter D and a taper portion on one end of the effective straight base, when the glass base material is attached to a drawing apparatus, a ratio ?/D between the average outside diameter D and a taper portion distortion ? is ?/D<=0.03, and the taper portion distortion ? is expressed with a maximum value of a center-line displacement amount of the glass base material between an effective straight base end from the taper portion and a distortion evaluating end of the taper portion.

Abstract: The present invention relates to a preform for a glass ferrule and a fabrication method thereof. It is an objective of the present invention to fabricate dual hole ferrules having various distances between two holes by using a single preform. It is another objective of the present invention to fabricate a preform for a dual hole glass ferrule by a simple process. To meet the above and other objectives, the present invention provides a preform for a glass ferrule, comprising two holes which are formed through the preform and exit out both side cross-sections of the preform, wherein the two holes are symmetrical to the center in a diameter direction of the preform and a distance between the two holes changes in a lengthwise direction of the preform.

Abstract: There is provided an elongating method of an optical fiber base material which can easily correct a distorted portion of an optical fiber base material with it being possible to elongate the optical fiber base material to reduce its diameter. According to such an elongating method, in an elongating process of elongating an optical fiber base material by heating the optical fiber base material in a heating furnace so that a diameter of the optical fiber base material is reduced, before the optical fiber base material is elongated from an end thereof, a distorted portion of the optical fiber base material is connected by being heated to be softened in the heating furnace. To do so, the optical fiber base material is attached to a hanging mechanism so as to be hung in an electric furnace, the distorted portion of the optical fiber base material is heated to be softened.

Abstract: A deposition system for depositing a chemical vapor onto a workpiece, including a deposition chamber having a plurality of components for performing chemical vapor deposition on the workpiece. The deposition chamber includes an inner skin made of Hasteloy for sealing the plurality of components and the workpiece from the air surrounding the deposition system, and an outer skin that encloses the inner skin and is separated from the inner skin by an air gap. The outer skin includes vents that create a convection current in the air gap between the inner skin and outer skin of the deposition chamber. The deposition system also has a gas panel for regulating the flow of gases and vapors into the deposition chamber, and a computer for controlling operation of the gas panel and the components in the deposition chamber.

Abstract: A deposition system for depositing a chemical vapor onto a workpiece is disclosed, including a deposition chamber having a plurality of components for performing chemical vapor deposition on the workpiece. The deposition chamber includes an inner skin made of Hasteloy for sealing the plurality of components and the workpiece from the air surrounding the deposition system, and an outer skin that encloses the inner skin and is separated from the inner skin by an air gap. The outer skin includes vents that create a convection current in the air gap between the inner skin and outer skin of the deposition chamber. The deposition system also has a gas panel for regulating the flow of gases and vapors into the deposition chamber, and a computer for controlling operation of the gas panel and the components in the deposition chamber.

Abstract: A random array of holes is created in an optical fiber by gas generated during fiber drawing. The gas forms bubbles which are drawn into long, microscopic holes. The gas is created by a gas generating material such as silicon nitride. Silicon nitride oxidizes to produce nitrogen oxides when heated. The gas generating material can alternatively be silicon carbide or other nitrides or carbides. The random holes can provide cladding for optical confinement when located around a fiber core. The random holes can also be present in the fiber core. The fibers can be made of silica. The present random hole fibers are particularly useful as pressure sensors since they experience a large wavelength dependant increase in optical loss when pressure or force is applied.

Abstract: A coating is applied on an optical fiber drawn from a melted tip of an optical-fiber preform. A glass spin is applied to a coated optical fiber by gripping the coated optical fiber with at least a pair of spinning applying rollers arranged in different levels with parallel rotation axes, rotating the spinning applying rollers so that the coated optical fiber is guided in a predetermined direction, and alternately shifting the spinning applying rollers in opposite directions along the rotation axes. The glass spin is applied to the coated optical fiber in a state in which each of the rotation axes is tilted at a predetermined angle from a plane perpendicular to the first direction.

Abstract: An optical fibre coupling structure comprising an optical fibre having an elongate input surface and shaped so that the diameter of the core of the fibre reduces in one dimension away from the input while increasing in the other dimension away from the input to form respective convergent and divergent surfaces, towards an output which is more circular than the input.

Abstract: An optical fiber array substrate 11 has, in one surface thereof, eight V-grooves 12 for securing eight optical fibers 14 aligned in parallel to each other, and V-shaped side grooves 13 formed outside of the respective outermost V-grooves 12 located at the opposite sides of the substrate 11. The apexes of the outside ridges 12c and 12d defining the outermost V-grooves 12 are at the same height as the apexes of the inside ridges 12a and, the height of the bottom 13a of the side groove 13 is lower than that of a contact point 12e between the ridge line of the V-groove 12 and optical fiber 14.

Abstract: An optical fibre arrangement has at least two optical fibre sections, each optical fibre section defining an outside longitudinally extending surface. The outside longitudinally extending surfaces are in optical contact with each other. The invention further provides for an amplifying optical device have an optical fibre arrangement as just described, and a pump source. The amplifying optical device is configured such that the pump source illuminates the amplifying optical fibre. A amplifying arrangement is also disclosed. The amplifying arrangement includes a plurality of amplifying optical devices as just described, and each amplifier also has at least one input fibre and a first multiplexer connected to the input fibre. Each amplifier is configured such that at least one of the amplifying optical fibres is connected to the first multiplexer. The amplifying arrangement also has a second multiplexer connected to each of the first multiplexers.

Abstract: In a process for producing a low polarization mode dispersion optical fiber, which comprises the steps of drawing a glass preform into an optical fiber and of spinning, during drawing, the optical fiber about an optical fiber axis, the spinning is imparted according to a bidirectional and substantially trapezoidal spin function, which includes zones (P) of substantially constant amplitude (plateau) and zones of transition (T) where inversion of the spin direction takes place, wherein the extension (p) of the zones of substantially constant amplitude is greater than the extension (t) of the zones of transition, and the number of inversions of the direction of spin in a length of fiber of 20 m is at most two.

Abstract: A method for fabricating tapered optical fibers is provided. The method includes applying thermal energy at a location defined along an elongated length (114, 116, 118) of an optical fiber (112). The method also includes varying the location in a first direction of travel at a predetermined rate along the elongated length of the optical fiber while applying a tension to the optical fiber. The method further includes removing the tension when the location is outside a first portion (116) of the elongated length. According to an aspect of the invention, the method includes transitioning from the first direction of travel to a second direction of travel opposed to the first direction of travel when the location is within a second portion (114) of the optical fiber. The method further includes transitioning from the second direction of travel to the first direction of travel when the location is within a third portion (118) of the optical fiber.

Abstract: The invention is directed to polarizing devices that can be scaled to polarize electromagnetic radiation having wavelengths in ultraviolet to microwave range; and more particularly to devices suitable for use at visible and IR wavelengths. The device has a length, a width and a thickness, and a patterned system of channels, voids or holes embedded in or through a glass matrix and running through the thickness of the glass to thereby polarize incoming electromagnetic radiation having two polarization modes orthogonal to one another, blocking the passage of or reflecting one mode and permitting the other mode to pass through the device. The glass can be any glass suitable for transmitting the electromagnetic radiation in the range it will be used without excessive transmission losses due to absorbance of radiation in that range by moieties present in the glass.

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: Disclosed is a method for fabricating an optical fiber having attenuation loss, in which non-uniformity of the attenuation loss in the lengthwise direction of the optical fiber is equal to or less than 0.05 dB/km in the wavelength band of 1383 nm and an average value of the attenuation loss is equal to or less than 0.35 dB/km. The method comprising the steps of (a) fabricating a soot preform while maintaining an average temperature of a core surface at a level equal to or less than 1000° C. and temperature variation of the core surface according to a growing length of the soot preform in a range of ?10 to 10° C./cm, fabricating an optical fiber preform by dehydrating, consolidating and vitrifying the soot preform and (c) drawing the optical fiber from the optical fiber preform under a temperature range between 1900 to 2300° C.

Abstract: Embodiments of the invention include an optical fiber preform assembly and a method for making optical fiber using the preform assembly. The assembly includes a preform core rod, at least one overclad tube formed around the preform core rod, a handle attached to one end of the overclad tube, and a refractory material positioned in the overclad tube between the preform core rod and the handle. The refractory material reduces if not prevents movement of the preform core rod into the handle during the fiber draw process. Preferably, the refractory material is made of, e.g., magnesium oxide and/or aluminum oxide, and has a melting point, e.g., greater than approximately 2000 degrees Celsius. Embodiments of the invention also include a method for making optical fiber using this preform assembly.

Abstract: A method of making an optical fibre including providing an increased diameter portion on a rod. The rod is assembled by positioning the rod in a tube such that an annular gap is defined between an outer surface of the rod and an inner surface of the tube, and such that the increased diameter portion of the rod engages the tube and supports the rod with respect to the tube, and supporting the rod and tube assembly by gripping the tube. At the lower end of the rod and tube assembly, portions of the tube are collapsed onto the rod such that the tube portions fuse to the rod forming collapsed portions of the rod and the tube assembly. The collapsed portions are drawn to form an optical fibre. The vertically oriented rod and tube assembly can also be collapsed to form an optical fibre preform.

Abstract: In the known method for producing an optical fiber, a coaxial arrangement comprising a core rod and an outer jacket tube is elongated, the coaxial arrangement being supplied in a vertical orientation to a heating zone and being softened therein zonewise, starting with the lower end thereof, and the optical fiber being withdraw downwards from the softened portion, whereby an annular gap existing between core rod and jacket tube is collapsed. Starting therefrom, in order to provided a method which makes it possible to produce optical fibers with a minimum curl and at low costs, the invention suggests that a quartz glass cylinder treated mechanically to its final dimension and having an outer diameter of at least 100 mm should be used as the jacket tube. An optical fiber obtained according to the method is characterized in that without the action of external forces it assumes a radius of curvature of at least 6 mm.

Abstract: An optical cable for telecommunications having an optical core and a plurality of protecting and reinforcing elements or avers placed around the optical core. The optical core has a central reinforcing element, a polymer layer, a plurality of optical fibers incorporated in the polymer layer and a thin sheath which covers the polymer layer. The optical fibers have an alternating spin about their own axes with a maximum value of at least 4 twists per meter, and a core having a mean ellipticity in the range of 0.25 to 0.55, in such a way that the effects of birefringence of the fibers caused by the cabling process are significantly reduced.

Abstract: Based on an intermediate 20A in which a cladding portion 22 is formed on the outer periphery of a core portion 21, a pair of holes 23 and 24 are provided parallel to the z axis on both sides of the core portion 21 within the cladding portion 22, and an intermediate 20 is thereby fabricated. In this intermediate 20, a width Ry in the y-axis direction is made smaller than a width Rx in the x-axis direction. Moreover, a cylindrical stress applying part 33 is inserted into a hole 23 of the intermediate 20, and a cylindrical stress applying part 34 is inserted into a hole 24 thereof. Thus, a preform 40 is formed. These materials are drawn and integrated together, and a polarization maintaining optical fiber is thereby manufactured.

Abstract: A GRIN fiber lens is fabricated by the steps of providing a graded index glass preform, thinning the graded index preform to remove a sufficient thickness of the graded glass to establish a desired ?n, and drawing a graded index optical fiber from the thinned graded index preform. Thinning, in this context, refers to removal of graded index glass from the outside of the graded index preform so as to reduce its outer diameter. The thinning thus changes ?n which is the refractive index difference between the center of the preform and its outer surface. The graded index preform can be provided by MCVD deposition followed by removal of the starting tube glass, by OVD deposition, by VAD, or by ion exchange fabrication. The thinned graded index preform is advantageously annealed before drawing in order to minimize ripple. And, in a variation of the process, an overcladding can be applied over the thinned graded preform before draw for further adjustment or control of the ?n.

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: The present invention provides a method of elongating a glass preform having holes extending in the longitudinal direction while suppressing excess shrinkage of the holes. In the method of elongating a glass preform of the present invention, both ends of the glass preform having the holes extending in the longitudinal direction are held by a first holding member and a second holding member, respectively; and the glass preform is successively heat-melted from one of the ends by a heating means while the distance between the first holding member and the second holding member is increased in the longitudinal direction, to elongate the glass preform. The glass preform is elongated by heat-melting with the heating means in a manner such that the temperature T of the softened portion satisfies a relation represented by 11[° C./mm]·D+860[° C.]<T<17[° C./mm]·D+880[° C.

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: The invention relates to an optical waveguide (optical fiber) based on quartz glass having reduced internal mechanical stresses. In prior art optical waveguides, the internal mechanical stresses are primarily due to the production process, namely due to the difference of the linear thermal coefficients of expansion of the core and sheathing material during the cooling of the fiber and due to the drawing itself. In an inventive optical waveguide, the difference of the linear thermal coefficients of expansion of the core and/or sheathing material is selected by means of an appropriate doping of the core and sheathing material. This selection is made so that the internal mechanical stresses, which are caused by the cooling during the production process, are significantly reduced or eliminated and/or they counteract the stresses caused by the drawing.

Abstract: The specification describes an improved optical fiber design in which the criteria for high performance in a Raman amplified optical system, such as moderate effective area, moderate dispersion, low dispersion slope, and selected zero dispersion wavelength, are simultaneously optimized. In preferred embodiments of the invention, the dispersion characteristics are deliberately made selectively dependent on the core radius. This allows manufacturing variability in the dispersion properties, introduced in the core-making process, to be mitigated during subsequent processing steps.

Abstract: Disclosed is a method of producing an elliptic core optical fiber, in which a original preform having a circular core disposed at the center of a circular clad is processed to flatten on its periphery to form a processed preform that is then drawn with heating into an elliptic core optical fiber. According to the invention, the form of the processed preform used for producing an elliptic core optical fiber with desired specific dimensions can be designed using pre-obtained correlations based on the dimensions of the elliptic core optical fiber. If the processed preform designed like this is drawn with heating, an elliptic core optical fiber with desired specific dimensions can be reliably and easily produced.

Abstract: The method of manufacturing an optical fiber in accordance with the present invention comprises a step of yielding an optical fiber by drawing an optical fiber preform softened upon heating, wherein a temperature at which the optical fiber preform is softened is at least 1800° C., whereas the optical fiber preform or optical fiber has a glass cooling rate of 4000° C./sec or less when attaining a temperature of 1800° C.

Abstract: A drawing apparatus 1 comprises a drawing furnace 11, a protecting tube 21, and a resin curing unit 31. A buffer chamber 41 is disposed between the drawing furnace 11 and the protecting tube 21, and has a length L1 in the drawing direction of the optical fiber 3. The buffer chamber 41 is constituted by a first buffer cell 42 and a second buffer cell 45. In the space within the buffer chamber 41, an He gas, which is an atmosphere gas within the drawing furnace 11, and the air, which is an atmosphere gas within the protecting tube 21, exist in a mixed state. The optical fiber 3 drawn upon heating in the drawing furnace 11 is fed to the protecting tube 21, and a predetermined part of the optical fiber 3 is annealed at a predetermined cooling rate. Thereafter, a coating die 62 coats the optical fiber 3 with a UV resin solution 63, and the resin curing unit 31 cures the UV resin 63, whereby a coated optical fiber 4 is obtained.

Abstract: The invention relates to a method of fabricating an optical fiber with improved control of transmission characteristics. It proposes determining variations in the characteristics of the preform departing from the design characteristics and modifying the diameter of the fiber during drawing as a function of the measured variations. By varying the diameter of the fiber, variations in the preform departing from its design values can be compensated, in other words irregularities of the preform can be smoothed out. This variation limits the effect of preform variations on the propagation characteristics of the fiber.

Abstract: The drawing method of the present invention uses a drawing furnace comprising a furnace muffle tube, a furnace body and a heater. According to the method, an optical fiber preform is inserted from the inlet of the furnace muffle tube, the optical fiber preform is melted by means of a heater, under a specified gas atmosphere, and is drawn toward the outlet of the furnace muffle tube by means of a specified drawing tension. The optical fiber preform and the drawing furnace used in this method both satisfy the condition of below-indicated formula (1): L/D?8??(1) wherein L indicates the length of the furnace body in the drawing direction and D indicates the diameter of the optical fiber preform.

Abstract: High index-contrast fiber waveguides, materials for forming high index-contrast fiber waveguides, and applications of high index-contrast fiber waveguides are disclosed.

Abstract: A drawing apparatus 1 has a drawing furnace 11, a heating furnace 21, and a resin curing section 31. The drawing furnace 11 has a muffle tube 13 to which an He gas supply passage 15 from an He gas supply section 14 is connected so as to supply He gas. The optical fiber 3 drawn upon heating by the drawing furnace 11 is fed to the heating furnace 21, whereby a predetermined part of the optical fiber 3 is annealed at a predetermined cooling rate. The heating furnace 21 has a muffle tube 23 to which an N2 gas supply passage 25 from an N2 gas supply section 24 is connected so as to supply N2 gas. Thereafter, the optical fiber 3 is coated with a UV resin 39 by a coating die 38, and the UV resin 39 is cured in the resin curing section 31, whereby a coated optical fiber 4 is formed.

Abstract: A method for manufacturing an optical fiber comprises setting a heating condition for heating a glass rod, which is a parent material of the optical fiber, and an elongating speed of the glass rod based on a prescribed numerical value which changes with a progress of elongation of the glass rod; heating and elongating the glass rod to generate a preform based on the heating condition and the elongating speed which are set by the setting; and drawing the preform to a filament-like form by further heating the preform to generate the optical fiber.

Abstract: A method of measuring the twist imparted to an optical fibre includes the steps of advancing the optical fibre in a predetermined direction and at a predetermined velocity, imparting to the optical fibre, during the step of advancing, a twist about its axis, measuring the diameter of the optical fibre during the step of advancing, to generate a time-based signal indicating the diameter, and processing this signal to find a value indicating the imparted twist. The step of processing includes the principal steps of transforming in the frequency domain the signal relating to the measurement of the diameter, calculating the power spectrum of the signal thus obtained, distinguishing in this power spectrum the signal peaks correlated with the imparted twist, determining the maximum frequency associated with these signal peaks, and dividing the value of this maximum frequency by the value of the velocity of advance of the fibre to find the value indicating the imparted twist.

Abstract: Methods of fabricating an optical fiber preform and a method of fabricating an optical fiber of the invention realize the fabrication of an optical fiber having desirable transmission characteristics in the entire wavelength rage of about 1.3 to 1.6 &mgr;m. The fabrication method comprises a porous core rod producing step of depositing a first cladding (3) having an outer diameter D so as to surround a core (2) having an outer diameter d to produce a porous core rod (1) of D/d≧4.0 by VAD. Then, the porous core rod (1) is dehydrated to reduce the OH group concentration to 0.8 ppb or less by weight ratio. The porous core rod (1) is formed to be transparent for a vitrified core rod (4) and is heated and stretched. Thereafter, a second cladding is obtained by depositing a second porous cladding (5) around the vitrified core rod (4) by VAD to be dehydrated, transparent and vitrified.

Abstract: The invention is directed to the production of optical fibers from optical fiber preforms using flow physics. The present methods provide for the “drawing” of an optical fiber preform using focusing of the preform by a surrounding fluid, e.g. a heated gas.

Abstract: A furnace for drawing an optical fiber provided with a muffle tube (10) and inner tubes (5,5′) connected to the upper end of the core tube, wherein a preform (1) supported by a dummy rod (2) at the upper part thereof is disposed inside the muffle tube (10) and inner tubes (5,5′) so as to be movable downward together with dummy rod (2), the preform (1) is heated and melted by a heater (11) from the outside of the muffle tube (10) and an optical fiber (1a) is pulled out from the lower end of the preform (1); the furnace is further provided with one or a plurality of sets of separating plates (4, 17) adapted to partition a space in the inner tubes (5,5′) above the preform (1) into a plurality of portions in the advance direction of the preform and disposed in the space, and with gas blowing inlets (8) disposed in the parts of wall surfaces of the inner tubes (5,5′) which are below the separating plates (4, 17) and adapted to blow an inert gas into the inner tubes (5,5′) and the muff