Abstract: In joining an optical fiber containing twin cores to a corresponding optical fiber of standard type having a single core and having the same outer diameter, so that a core in the twin-core fiber is aligned with the core in the standard fiber, a conventional automatic splicing machine for optical fibers is used. The twin-core fiber is placed with its cores for instance located in a vertical plane. Then the fibers are spliced in a conventional manner with an alignment of the outer surfaces of the fiber ends and during the splicing procedure or from the finished splice the lateral offset of for instance the upper core of the twin-core fiber and the single core is determined. This can be carried out by capturing an image of the fiber splice in a heated state, when the splice is performed by fusion-welding. The determined offset value then gives the offset, which is to exist between the outer surfaces of the fiber ends for providing the correct alignment of the fiber cores.

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: In a method of shrinking a tubular optical fiber preform with a doped silica core the preform is placed on a glassmaking lathe to rotate it about an axis, a torch is moved parallel to the axis in front of the preform to shrink it and collapse it in a number of passes, and during an etching pass a mixture of oxygen and a fluorine precursor gas is injected through one end of the incompletely collapsed preform to eliminate a certain layer from the core. During the etching pass, a certain value of the pressure of the gaseous mixture at the end of the preform is determined and the speed of the torch is slaved to this pressure value. Controlling the speed of the torch stabilizes the pressure of the gaseous mixture inside the preform, which longitudinally homogenizes the diameter of the core and the refractive index difference relative to an optical cladding around the core.

Abstract: A large optical preform 303 is made by a modified chemical vapor deposition (MCVD) process by depositing successive layers of core and cladding materials onto the inside surface of a rotating glass tube 33 having a hydroxyl ion (OH.sup.-) level that is less than 0.5 parts per million (ppm) by weight. The tube is then collapsed inwardly to form a core rod 301 in which the deposited core material 31 has a diameter that is greater than about 5 millimeters and the deposited cladding material 32 has an outside diameter that is less than about 15 millimeters. A machine-vision system 140, 150, 160 monitors and controls the diameter of the glass tube by regulating the pressure within the tube. Moreover, the machine-vision system monitors and controls the straightness of the tube by varying its rotational speed according to angular position. After the core rod 301 is formed, it is plasma etched to remove contaminants, and then overclad with two glass jackets 34, 35 having a hydroxyl ion (OH.sup.

Abstract: An automated method and apparatus for making optical fiber couplers is disclosed. The apparatus includes various processing stations under the control of a programmable controller. A fiber feeding system receives a set of optical fibers from a reel and guides them to the various processing stations. The fibers are guided into a fiber insertion fixture. The insertion fixture moves the fibers to the aperture of a glass capillary tube. The fibers are then stripped of a portion of their coating. The feeding system feeds the stripped fibers through the insertion fixture and into the glass tube. The fibers are severed and terminated. Subsequently, a burner heats the glass tube, causing it to collapse around the fibers to form a fiber coupler.

Abstract: There are provided an optical fiber rod overcladding apparatus and method, and an optical fiber drawing method. In the preform rod overcladding method, a preform rod is clamped in a top chuck and leveled, and a glass tube is mounted in a bottom chuck and leveled. The preform rod is coaxially inserted into a glass tube. Then, the glass tube is preheated by the furnace and heated by the burner until the glass tube reaches a softening point. The preform rod is completely sealed in the glass tube by sucking air in a clearance between the preform rod and the glass tube by application of a negative vacuum pressure. Thus, a preform is completed.

Abstract: A method for producing a glass preform by synthesizing a porous glass preform by a vapor-phase synthesizing method and heating said porous glass preform in a vacuum or reduced-pressure atmosphere so as to consolidate said porous glass preform, which comprises the steps of: a first step of degassing said porous glass preform to thereby remove gas adsorbed or contained therein; a second step of temporarily contracting said porous glass preform at a temperature higher than a temperature in the first step and lower than a consolidation temperature; and a third step of consolidating said porous glass preform at the consolidation temperature; the degassing of said first step is determined in accordance with the bulk density of said porous glass preform.

Abstract: The production of mineral fibers by centrifuging on rollers (3, 4, 5, 6) with horizontal axes from a stream (1) of molten material includes determining the relative position of the stream (1) of molten material in relation to the first roller (3), and controlling this position by use of CCD cameras (8, 11, 40). A camera (11) observes the periphery of a fiber-drawing roller (4).

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: Man made vitreous fibers are made using a cascade of rotors (4, 5, 6, 7) from melt poured onto the top rotor (4) wherein the melt has a low viscosity (not more than 18 poise) at 1400.degree. C. and has a viscosity of not more than 10 poise on the top rotor (4), the top rotor has an acceleration field of at least 30 km/sec.sup.2, and the second rotor (5) is arranged with its center on a line with the center of rotor (4) which makes an angle C of 0-20.degree. and has an acceleration field of 50 to 150% of the field of the rotor (4), and the subsequent rotors (6, 7) have an acceleration field of 120 to 250% of the acceleration field of the rotor (4).

Abstract: To compensate for disturbing influences during arc welding of at least two optical waveguide fiber ends, an impedance of the discharge path of the arc is measured and at least one of the welding parameters is varied based on the measured impedance.

Abstract: An optical fiber preform is made by supplying the base glass reactant and the dopant glass reactant to a burner that generates a flame in which a stream of glass particles is produced. The burner moves with respect to a rotating mandrel to deposit layers of glass particles on the mandrel. During the deposition of a portion of the preform, the flow rate of the dopant glass reactant is varied in accordance with a first recipe of dopant flow as a function of burner position as the burner moves longitudinally along the substrate to form one of the layers. The flow rate of the dopant glass reactant varies in accordance with a second recipe of dopant flow as a function of burner position as the burner moves longitudinally along the substrate to form a layer adjacent to the one layer. The second recipe is different from the first recipe, and the flow rate of the dopant glass reactant changes during the step of moving the reaction zone to form the one layer.

Abstract: Measurement of the delamination resistance of polymer coated optical fiber can provide valuable information for quality control and/or coating development, and a method of making polymer coated optical fiber that includes determination of the delamination resistance is disclosed. Also disclosed is apparatus that facilitates determination of the delamination resistance.

Abstract: In a soot-deposition container, raw material gas and at the tip of a starting glass rod, combustion gas, and carrier gas are supplied to a core-depositing burner and raw material gas, combustion gas, carrier gas, and gas for doping of fluorine are supplied to a cladding-depositing burner, thereby forming porous glass soot comprised of glass soot for core and glass soot for cladding. With growth of soot, the supply amount of the fluorine-doping gas is increased while supply amounts of the other gases are kept constant. Next, dehydration process and transparentizing process of soot are carried out to obtain a glass preform for optical fiber. Fabricated in this way is the glass preform for optical fiber having the silica glass portion doped with low-concentration fluorine with high uniformity in the growth direction.

Abstract: An improved method of coating an optical fiber is disclosed. A transducer is submerged in a container of liquid coating material and activated so that it causes the formation of a wave of coating material within the container. The optical fiber is then drawn through the container and through the wave, the wave counterbalancing the negative meniscus produced by drawing the fiber through the container. A curved housing also may be placed in the container and surrounding the transducer for controlling the size, amplitude, shape, or direction of the wave. A plurality of transducers also advantageously may be used.

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: During the fire-polishing of a lengthwise extended glass body (3), for example a preform for drawing optical fibers, the glass body (3) is held by a holding device (5, 7), and is heated by a burner (23) moving at a variable advancing speed parallel to the lengthwise axis (19). The surface temperature of the glass body (3) is determined with a temperature measuring device (25). The mechanical stress condition of the glass body (3) is detected with an optical device (29) and can be controlled by varying the burner temperature and/or the advancing speed of the burner. The invention makes it possible to counteract the occurrence of high mechanical stresses in the glass body (3).

Abstract: An improvement is proposed, in a method for the preparation of a step-index silica glass preform as a precursor of optical fibers by completing the cladding layer of the secondary preform by the outer deposition on and around a primary preform consisting of the center core and side core, to conduct the outer deposition for the cladding layer in such a way that the inequality.vertline.d.lambda..sub.0 /dk.vertline..ltoreq.500 nmis satisfied, in which k is the ratio of the diameter of the primary preform to the diameter of the secondary preform and .lambda..sub.0 is the zero-dispersion wavelength in nm of an optical fiber obtained by drawing the secondary preform, d.lambda..sub.0 /dk being the differential of a function held between .lambda..sub.0 and k determined beforehand from the distribution of the refractive index within the primary preform.

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: The present invention relates to a process wherein a large glass preform is flame abraded to have a clear and smooth surface. In particular, the present invention pertains to a method for flame abrading a surface of a rotating glass preform by an oxyhydrogen flame which moves along a length of the glass preform, in which a movement velocity of the oxyhydrogen flame or a flow rate of oxyhydrogen of the oxyhydrogen flame is varied to conduct the flame abrasion treatment.

Abstract: The present invention relates to a process for producing a porous glass preform for an optical fiber and an apparatus for conducting such a process. According to the process, fine glass particles are produced by heating and reacting vaporous starting materials in a reaction vessel. The resulting fine glass particles are thereafter deposited to obtain the porous glass preform. An exhaust gas containing non-deposited fine glass particles is exhausted through an exhaust duct at a velocity above 15 m/sec. Preferably, pressure fluctuation in the reaction vessel is minimized by supplying air from outside of the reaction vessel to the exhaust duct. In accordance with the present invention, the exhaust duct is less likely to become obstructed by non-deposited fine glass particles. As a result, the preform can be produced without interruption over an extended period of time.

Abstract: The present invention provides a method for manufacturing an optical fiber coupler in which an optical fiber is elongated and heated by using a heating source under a constant tension. The heat source is controlled based on the ratio of a target elongating speed and an actual elongating speed of the optical fiber.

Abstract: Disclosed is an improved device and method for detecting fiber breakouts and fiber restarts in processes or systems for making fibers from a molten thermoplastic material. In these processes the running fibers induce ambient air into the array of hot fibers close to the nozzles where the fibers are formed, but this air flow essentially ceases when the fiber breaks out. A thermocouple junction located in the path of this airflow will sense temperature changes caused by fiber breakouts and fiber starts. The present invention simplifies and increases the accuracy of prior art sensor systems by eliminating hardware holding this thermocouple and instead uses one or more small holes in a bushing frame plus the refractory used to hold the fiberizing bushing in the frame to hold the thermocouple in the appropriate place.

Abstract: In the method for forming an optical waveguide according to this invention, an optical waveguide comprising a core of quartz as a main component, and a cladding layers surrounding the core is formed by deposition of glass fine particles by flame hydrolysis deposition and vitrifying the glass fine particle layers. This method includes a step of transiently increasing a feed amount of phosphorus to a flame burner in forming glass fine particle layers to be the cladding layers. Feeding phosphorus in this step for the first time after a glass fine particle layer is deposited without feeding phosphorus to the flame burner, whereby generation of foreign objects near the core dan be suppressed.

Abstract: The present invention provides a method of manufacturing an optical component, having the steps of forming a first position aligning pattern on a surface of a substrate, forming a second position aligning recess-projection pattern conforming with the first position aligning pattern and a third position aligning recess-projection pattern having a predetermined positional relationship with the second position aligning recess-projection pattern, and applying a predetermined processing with the third position aligning recess-projection pattern used as a reference under a predetermined positional relationship with the first position aligning pattern.

Abstract: A method and apparatus for continuously producing an endless thermoplastic material, such as yarn or tape, and winding the material into a package. A physical parameter of the package, such as its diameter or weight, is monitored, and a control signal is generated which is a function of the monitored physical parameter. The control signal is then compared to a predetermined reference signal, and an output signal is generated when the difference between the control signal and the reference signal exceeds a predetermined deviation. The output signal thus represents the quality of the material in the package, and it may be used to permit classification of the final product or to control the operating conditions of the apparatus so as to maintain a desired quality level.

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.