Abstract: A method for manufacturing optical fiber with enhanced photosensitivity comprising the step of: forming a molten layer of glass and drawing a fiber from the molten layer of glass at a temperature of between about 1900° C. and 1995° C. Draw tension can be adjusted to attain the desired draw speed.

Abstract: In a known method for the manufacture of a tube made of a vitreous material, especially of quartz glass, a hollow cylindrical semifinished product made of a vitreous material is carried essentially vertically to a heating zone, wherein it is heated and drawn off downwards—without the use of tools—to the tube by forming a transitional area from semifinished product to tube, while diameter and wall thickness of the tube are continuously measured, and the tube's measured geometrical data being used to generate a control signal with the aid of which a pressure difference is regulated between pressure P1 in the interior space of the semifinished product, the transitional area and the tube, as well as pressure P2 in the heating chamber which is regulated in the heating zone at least in the transitional area from semifinished product to tube and its adjacent tube area.

Abstract: After the start of the control operation of a drawing apparatus, the operation control of a line speed being the drawing-in speed of an optical fiber is performed by a line speed control unit (19), and an optical-fiber feed speed control is performed by a preform feed speed control unit (22), in order that an optical fiber outside diameter measured by an optical-fiber outside diameter measurement unit (8) may become a target outside diameter. By way of example, in a case where the distal end of an optical fiber preform is not in a shape steadily melted in a heating furnace, the preform speed control unit (22) controls the feed speed of the optical fiber preform in the three stages of an optical-fiber-preform initial feed speed control, an acceleration-associated preform feed speed control and a line speed-associated preform feed speed control.

Abstract: The present invention relates to a sizing composition for a glass yarn, consisting of a solution whose solvent content is less than 5% by weight, this solution comprising at least 60% by weight of polymerizable components, at least 60% by weight of these polymerizable components being components with a molecular mass of less than 750 and these polymerizable components comprising at least one mixture capable of polymerizing: of component(s) containing at least one reactive acrylic function and/or at least one reactive methacrylic function, and of component(s) containing at least one reactive primary amine function and/or at least one reactive secondary amine function, at least 20% of the polymerizable components containing at least two reactive functions chosen from acrylic, methacrylic, primary amine and secondary amine functions.

Abstract: A manufacturing method of an optical fiber, which enables to precisely manufacture the optical fiber having a desired chromatic dispersion, comprising: (1) preparing an optical fiber preform having a longitudinally uniform refractive index, (2) measuring the chromatic dispersion of a predetermined length of the optical fiber obtained at the beginning of the drawing, (3) according to the results of such measurement, estimating the chromatic dispersion characteristic of the optical fiber obtained by drawing the optical fiber preform, and commencing the drawing of the optical fiber preform. To achieve the target chromatic dispersion diameter of the optical fiber is determined according to the chromatic dispersion that is measured with respect to a predetermined length of an optical fiber obtained at the beginning of the drawing of an optical fiber preform. Then, the remainder of the optical fiber preform is drawn to produce an optical fiber having the desired chromatic dispersion.

Abstract: In a method of elongating a glass preform comprising the steps of holding both ends of the glass preform 1a with a first holding section 2 and a second holding section 3, respectively; moving the first holding section 2 and the second holding section 3 in a longitudinal direction of the glass preform 1a with the moving speed of the first holding section 2 faster than that of the second holding section 3 and, at the same time, heating and softening the glass preform 1a by a heating section 4 successively; and elongating the glass preform 1a by a tensile force applied thereto, so as to form an elongated body 1c; an electric furnace is employed in the heating section 4; and said method further comprising the steps of setting a reference value R1 with respect to an outside diameter at a specific position 1d in a tapered region 1b in the glass preform 1a in the process of elongating; acquiring an actually measured value R2 at the specific position 1d; and controlling the moving speed of the first holding section 2

Abstract: A method for producing an optical fiber preform comprising inserting a core glass rod for use in the optical fiber preform into the quartz glass tube for the optical fiber preform and then welding them in a heating furnace to melt weld them together into a monolithic product, wherein the melting is started in such a state that the lower open edge of said quartz glass tube is placed inside the heating furnace and a gas is supplied from the upper edge of the tube, and after the lower edge portion of the quartz glass tube is drawn out from said heating furnace by melt deformation and stretching by the gravitational force, the gas supply is cut off and the pressure is reduced.

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 test optical fiber section (F) that resides under tensile stress (F) is heated in at least one longitudinal location so that a constriction (&Dgr;d) of its outside circumference forms thereat. This constriction (&Dgr;d) is acquired and utilized for setting welding parameters.

Abstract: Method for winding a fiber element onto a support. The fiber element having at least two longitudinal portions (Pi) with different characteristics. The method including the steps of supplying the fiber element to the support and associating with each longitudinal portion a respective value of the winding pitch (pi) which is different from the values associated with the portions adjacent thereto. The winding pitch associated with each portion being modulated in accordance with a periodic function.

Abstract: The method consists of increasing the flowrate of argon injected into the bottom of a fiber-drawing furnace when a weld between two sections of a preform is being drawn during the operation of drawing a fiber from a preform. This prevents the weld causing an excessive increase in the diameter of the resulting fiber and/or an excessive variation in the drawing speed.

Abstract: The invention is a method of making an optical fiber or cane (600) that has optical properties that vary axially. Core glass (100) and clad glass (200) are fed into a furnace to form the cane or fiber. The velocities of the feeding of the clad and core are controlled so that the total combined mass per unit time is constant. The diameter of the core (604) varies along the length of the fiber or cane in accordance with the control of the velocities. The variance in the core diameter results in the variance of the axial optical properties of the fiber or cane.

Abstract: A cooler of an optical fiber draw tower, situated below a melting furnace for melting a preform for an optical fiber, for cooling the optical fiber drawn from the preform melted in the melting furnace, includes at least one heat exchanger installed with a predetermined length surrounding the optical fiber drawn from the melting furnace, for cooling the drawn optical fiber. The heat exchanger is formed of a thermoelectric cooler (TEC) for taking electrical energy through one heat absorbing surface to emit heat to the other heat emitting surface and has a tubular shape in which the heat absorbing surface of the TEC surrounds the optical fiber drawn from the melting furnace along the drawing direction by a predetermined length, and the drawn optical fiber is cooled as it passes through the tubular TEC. Also, the cooler further includes an auxiliary cooler attached to the heat emitting surface of the TEC, for cooling the emitted heat.

Abstract: When drawing an optical fiber from a preform, positive and negative dispersion sections of an optical fiber are provided, respectively, with target glass diameters different from each other, whereby the positive and negative dispersion sections attain their respective desirable values of chromatic dispersion. Also, the positive and negative dispersion sections and a transient section therebetween are provided, respectively, with values of control constant different from each other, which are used to converge the measured glass diameter to said target diameter, for adjusting the drawing speed, whereby the transient section is shortened. Alternatively, the positive and negative dispersion sections of the optical fiber are provided with respective target drawing speeds different from each other, whereby the transient section is shortened.

Abstract: A double crucible fiber fabrication system employing a rod to control flow of the core material to produce a core of desired diameter. The rod fits closely within the inner crucible and moves at a speed necessary to produce a core material flow rate which will produce a desired core diameter. Control of the rod speed produces good control of core diameter for a wide variety of different core materials. It is also possible to control the rod speed in order to compensate for capillary effects and leakage of core material. Furthermore, control of the rod speed allows fabrication of a fiber having a core diameter which varies as desired throughout a single fiber.

Abstract: In the manufacturing of optical fiber preform with excellent accuracy of outer diameter made of the rod as drawn from synthetic quartz ingot, the outer diameter measuring devices 67 and 68 measure the outer diameters of the cone 2 and rod 3 drawn from the ingot 1, and the drawing speed is controlled based on the measured outer diameters. The optical fiber preform manufacturing apparatus that finishes the rod into truly round form without any curve has a rotary holding means 13 and 14 that hold the rod 3 resulting from the heating and drawing of the ingot 1 rotating it in synchronization with the rotation of the ingot 1, a comparison device 18 that outputs a signal after comparing the outer diameter of the cone 2 as measured by the outer diameter measuring device 11 with that of the referential circle, a control device 19 that controls the rotational amount of the rotating device 10, and a control device 20 that controls the rotational amount of the rotary holding device 13 and 14.

Abstract: A supplemental controller for a fiber glass bushing actively performs heating and cooling of a connected segment of the bushing which is otherwise controlled by a primary controller. In one embodiment, the supplemental controller performs heating by means of current injection into a connected bushing segment and cooling by means of current diversion from or around the connected bushing segment. Initial start-up and balancing operations can be performed without activation of the supplemental controller. In another embodiment of the invention, the supplemental controller heats a bushing segment by injecting current in-phase with current from the primary bushing controller and cools the bushing segment by injecting current out-of-phase with current from the primary bushing controller.

Abstract: A method for drawing a glass ingot into a rod having a given outer diameter is described. The method is characterized in that when the glass ingot is fed into a heating zone at a final tapered portion thereof, a temperature in the heating zone is decreased so that the final tapered portion is prevented from being drawn in excess owing to the heat from the heating zone.

Abstract: Fused biconical tapered couplers formed from the pulling of heated optical fibers have controllable coupling ratios by dynamically adjusting the heat intensity and pull speed during fabrication. Fiber coupler fabrication begins by arranging two optical fibers, heating the optical fibers using a heat source a predetermined distance from the optical fibers, and pulling the optical fibers at an initial pulling velocity as the heated optical fibers soften. The heat source is moved away from the optical fibers and the pulling velocity is selectively reduced in response to a substantial change in the detected coupling ratio. Changes in the coupling ratio are controlled by selectively reducing the pulling speed and the heat intensity to a point where the pulling of the optical fibers may be halted, and the heat removed, without a substantial change in the detected coupling ratio. The coupling ratio may be monitored at different wavelengths for fabrication of wideband couplers and wavelength division multiplexers.

Abstract: A glass blank is sent to a heating zone where it is softened region by region and drawn continuously in a controlled manner as a drawing bulb is formed. Estimates of at least one controlled variable are predicted free of dead time; in addition, at least one geometric variable of the component which can be correlated with the controlled variable is measured continuously, and the measurement values thus obtained are used to adjust the predicted estimates. On the basis of the predicted estimates thus adjusted, the nominal-actual deviation of the controlled variable is determined and converted to a change in a controlling variable. To ensure the production of a component with especially high dimensional accuracy, a geometric variable is measured at a first measurement site in the area of the drawing bulb for the prediction of the estimate, and the temperature of the drawing bulb be measured and used as a controlled variable.

Abstract: When one strand, which is formed by gathering a multiplicity of glass filaments having a diameter of 9.mu. or less and formed by drawing molten glass flowed out through a multiplicity of orifices formed in the bottom portion of a bushing, is wound around a collet, the strand is wound to form a square-end cheese package by traversing the strand by a traversing device having a constant amplitude, while the strand is brought into contact with a rotative drum of a tension relaxing device to reduce the tension acting on the strand. Thus, the quality of a package of non-twisted glass yarn having a monofilament diameter of 3 to 9.mu. can be improved, a large quantity of the package can be formed, and the package can easily be transported.

Abstract: Fused biconical tapered couplers formed from the pulling of heated optical fibers have controllable coupling ratios by dynamically adjusting the heat intensity and pull speed during fabrication. Fiber coupler fabrication begins by arranging two optical fibers, heating the optical fibers using a heat source a predetermined distance from the optical fibers, and pulling the optical fibers at an initial pulling velocity as the heated optical fibers soften. The heat source is moved away from the optical fibers and the pulling velocity is selectively reduced in response to a substantial change in the detected coupling ratio. Changes in the coupling ratio are controlled by selectively reducing the pulling speed and the heat intensity to a point where the pulling of the optical fibers may be halted, and the heat removed, without a substantial change in the detected coupling ratio. The coupling ratio may be monitored at different wavelengths for fabrication of wideband couplers and wavelength division multiplexers.

Abstract: A method of measuring the tension of drawing an optical fiber by means of the oscillation waveform of the optical fiber being drawn according to the invention can accurately, reliably and easily detect a peak frequency in the frequency spectrum of an oscillation waveform without being affected by noise. With the method of measuring the tension of an optical fiber being drawn by determining the fundamental oscillation frequency of the optical fiber from a peak in the spectrum of the linear oscillation waveform of the optical fiber, the detection of a peak frequency in the frequency spectrum of a linear oscillation waveform comprises steps of conducting an initial detecting operation over a frequency range expected to contain a peak frequency and conducting subsequent detecting operations over respective frequency ranges obtained by sequentially aligning the median frequency with the peak frequency detected in the immediately preceding detecting operation.

Abstract: Fiber optic devices are manufactured in an automated environment using a combination of clamps to secure the optical fibers and movable gripping devices that transport the optical fiber during the fabrication process while maintaining control of the ends of the optical fibers. An optical fiber from a spool is removed by a despooling arm having a gripping device, and moveable grippers thread the optical fiber into a set of clamps and place the end of the optical fiber in a clamp designed to splice the fiber optic end to a lead of a testing device. The fiber optic device is formed by dynamically controlling the heating and pulling process based on detected coupling ratios, and hermetically sealed while secured within the clamps. The sealed fiber optic device is moved for testing or packaging using a transport arm having a series of clamps to maintain the position of the fiber optic device and the ends of the leads of the fiber optic device.

Abstract: Disclosed is a method of controlling the diameter of a glass rod drawn from a glass preform. The diameter control begins as soon as a glass gob begins to move away from a heated portion of the preform. The velocity of the gob is measured and furnace temperature adjusted to maintain gob velocity at a pre-selected target value. By starting diameter control at this early stage of the process, utilization of the preform is improved as is the utilization of the drawing equipment.

Abstract: A method of drawing an optical fiber preform to manufacture an optical fiber, includes the steps of heating an optical fiber preform to temperatures at which the heated preform can be drawn, drawing the heated optical fiber preform by applying tension to the preform, and making the tension substantially constant during the drawing step. The particular method permits manufacturing an optical fiber exhibiting uniform transmitting characteristics, particularly uniform transmission loss, over the entire lengthwise region of the optical fiber, even if the optical fiber is manufactured by drawing an optical fiber preform having a large diameter.

Abstract: Fused biconical tapered couplers formed from the pulling of heated optical fibers have controllable coupling ratios by dynamically adjusting the heat intensity and pull speed during fabrication. Fiber coupler fabrication begins by arranging two optical fibers, heating the optical fibers using a heat source a predetermined distance from the optical fibers, and pulling the optical fibers at an initial pulling velocity as the heated optical fibers soften. The heat source is moved away from the optical fibers and the pulling velocity is selectively reduced in response to a substantial change in the detected coupling ratio. Changes in the coupling ratio are controlled by selectively reducing the pulling speed and the heat intensity to a point where the pulling of the optical fibers may be halted, and the heat removed, without a substantial change in the detected coupling ratio. The coupling ratio may be monitored at different wavelengths for fabrication of wideband couplers and wavelength division multiplexers.

Abstract: An apparatus for fabricating an optical fiber coated with metal, constructed with a crucible for melting the optical fiber preform to draw an uncoated optical fiber, a diameter measuring device for measuring the diameter of the uncoated optical fiber to regulate it, a metal coater for coating the uncoated optical fiber with metal to prevent penetration of moisture, a temperature controller for controlling the inside temperature of the metal coater, a post-cooler for cooling the metaled optical fiber from a high temperature, a capstan for drawing the optical fiber from the optical fiber preform by applying a rotational force against a portion of the metaled optical fiber, and a spool for winding the metaled optical fiber. The metaled optical fiber includes a core for transmitting light, a cladding on the core having lower refractive index than the core, and a metal coating formed on the cladding for preventing penetration of moisture.

Abstract: Fused biconical tapered couplers formed from the pulling of heated optical fibers have controllable coupling ratios by dynamically adjusting the heat intensity and pull speed during fabrication. Fiber coupler fabrication begins by arranging two optical fibers, heating the optical fibers using a heat source a predetermined distance from the optical fibers, and pulling the optical fibers at an initial pulling velocity as the heated optical fibers soften. The heat source is moved away from the optical fibers and the pulling velocity is selectively reduced in response to a substantial change in the detected coupling ratio. Changes in the coupling ratio are controlled by selectively reducing the pulling speed and the heat intensity to a point where the pulling of the optical fibers may be halted, and the heat removed, without a substantial change in the detected coupling ratio. The coupling ratio may be monitored at different wavelengths for fabrication of wideband couplers and wavelength division multiplexers.

Abstract: In accordance with the invention, a Ge-doped optical fiber having reduced Brillouin scattering loss is made by modulating the tension applied to the fiber during draw. The draw tension is modulated between a low range 10-50 g and a high in the range 150-250 g. The result is SBS suppression with no significant change to end-to-end fiber loss or dispersion factors.

Abstract: The present invention relates to a method for precisely elongating a glass preform of an optical fiber body having a desired outer diameter. In this method, a predetermined part of the glass preform is elongated as tensile stress is applied to one end of the glass preform while a predetermined part of the glass preform is heated and softened successively from one end toward the other end of the glass preform. In this elongating operation, while the outer diameter of the softening portion of the glass preform is measured, the tensile stress is adjusted such that the outer diameter of the softening portion coincides with a preset value of the control outer diameter. In particular, this method is characterized in that the preset value of the control outer diameter is changed at least during a predetermined period until termination of elongation or during a predetermined period from the start of elongation.

Abstract: A radiation resistant optical waveguide fiber doped with fluorine or drawn with low tension in the fiber. The fluorine doping is substantially constant across the core and a portion of the clad adjacent the core. The concentration of the fluorine is in the range of about 0.3 to 3.0 weight percent. The draw tension is less than or equal to about 5 grams (40 dynes/cm.sup.2) to achieve optimum radiation resistance. A synergy is found when fluorine and low draw tension are applied to a fiber. Improvement in radiation resistance is largely independent of fiber type and geometry. Further improvement in radiation resistance is found when germanium is doped in a portion of the clad adjacent the core.

Abstract: A method of manufacturing an optical module for wavelength-division multiplex optical transmission, which module comprises a first optical fiber having a first port at its one end and a second and a third optical fiber fused to the first optical fiber at its side face such that the first optical fiber is positioned in the center between the second and third optical fibers. The manufacturing method comprises a first step of regulating the aspect ratio at the fused portion while heating the fused portion and elongating the fused portion at zero speed or a very low speed and a second step of regulating the coupling length of the fused portion while elongating the fused portion at a higher speed than in the aspect ratio regulating step under the conditions of the heating temperature of the fused portion lowered and the aspect ratio kept unchanged.

Abstract: An apparatus and process for the production of a composite thread of glass and of organic material wherein continuous filaments of thermoplastic organic material are mixed in the form of a sheet with a bundle or sheet of glass filaments, with the speed of the thermoplastic filaments during their penetration into the bundle or sheet of glass filaments being greater than the speed of drawing of the glass filaments.

Abstract: A method and apparatus are provided for detecting irregular portions of an optical fiber which arise due to microscopic bubbles, bruises, and the like during an optical fiber drawing process. The present invention operates by varying the pulling rate of a pulling capstan based on feeding back measurements of the external diameter of the optical fiber to the pulling capstan. The ratio of a given pulling rate variation to a predetermined time period is then computed. The computed ratio is then compared to a previously specified value.

Abstract: An improvement is proposed in the process for the preparation of a porous silica glass preform as a precursor of optical fibers by the VAD method, in which fine silica particles produced by the flame hydrolysis of a silicon-containing compound are deposited on the lower end of a seed rod suspended at the lower end of a suspender rod rotated by a carriage in a vertical tubular reactor furnace to grow in the vertical direction. Instead of taking the fully grown porous preform out of the tubular furnace by pulling up as suspended on the suspender rod as is undertaken in the prior art, the seed rod is temporarily held by clamping with a holding device with disconnection from the suspender rod and the porous preform and seed rod are pulled up by a separate vertical driving device so that the overall height of the apparatus can be greatly decreased contributing to a reduction of the manufacturing cost of optical fibers of silica glass.

Abstract: An improvement is proposed in the apparatus and method for the preparation of a transparent silica glass preform as a precursor of optical fibers by sintering and vitrifying a porous silica glass preform in a sintering furnace as vertically suspended at the lower end of a suspender rod rotated by a carriage. Different from the conventional process in which the porous preform is lowered into the sintering furnace and the transparent preform after vitrification is pulled up out of the furnace as suspended at the lower end of the suspender rod throughout, a separate vertical driving device is provided along with a horizontal driving device for the carriage so that the effective up-and-down stroke of the carriage can be greatly reduced and the apparatus as a whole can be by far more compact contributing to the reduction of the manufacturing costs of the optical fibers of silica glass.