A method of manufacturing an optical fiber, the method includes drawing a first optical fiber preform at a first draw tension to produce a first alkali doped optical fiber and drawing the first optical fiber preform at a second draw tension to produce a second alkali doped optical fiber, measuring the attenuation of the first alkali doped optical fiber and the second alkali doped optical fiber such that the second alkali doped optical fiber has a lower attenuation. Additionally, the method includes setting the draw tension to the second draw tension and drawing a second optical fiber preform at the second draw tension to produce a third alkali doped optical fiber. The third alkali-doped optical fiber has an attenuation at 850 nm of about 1.50 dB/km or less and an attenuation at 1550 nm of about 0.155 dB/km or less.

A method for controlling the thickness of a glass ribbon and an article produced thereby are provided. The method includes: providing a glass ribbon by drawing from a melt or redrawing from a preform; predefining a nominal thickness of the glass ribbon; determining the thickness of the glass ribbon over its entire net width; determining at least one deviation of the thickness of the glass ribbon from the predefined nominal thickness; identifying the area of the thickness deviation in the glass ribbon; and heating the area of the at least one thickness deviation in the glass ribbon using a laser, so that the glass ribbon attains the predefined thickness.

Provided is an optical fiber manufacturing method that uses a low-cost large optical fiber preform having high precision. The optical fiber manufacturing method includes at least a positioning step of positioning core rods in a hollow carbon pipe that contains carbon as a main component, a soot preform preparation step of filling a gap between the carbon pipe and the core rods with silica powder that contains SiO.sub.2 as a main component, thereby producing a soot preform, a consolidating step of introducing the soot preform into a furnace and consolidating the silica powder, thereby producing a transparent intermediate preform from the soot preform, an extraction step of extracting the transparent intermediate preform from the carbon pipe, and a drawing step of drawing the transparent intermediate preform, thereby manufacturing an optical fiber.

A method for producing substrate tubes of quartz glass includes continuously supplying a hollow cylinder of quartz glass to a heating zone, softening the hollow cylinder zonewise in the heating zone, and drawing off a tubular strand from the softened portion. The hollow cylinder has an outer diameter C.sub.a, an inner diameter C.sub.i and an inner bore. The tubular strand has an outer diameter T.sub.a and an inner diameter T.sub.i. The following parameters are applicable to the hollow cylinder and the tubular strand: C.sub.a>180 mm, C.sub.r>3 with C.sub.r=C.sub.a/C.sub.i, T.sub.r<1.6 with T.sub.r=T.sub.a/T.sub.i and C.sub.i/T.sub.i<2.5. The blow pressure in an inner bore is adjusted to a value in the range of 4 to 10 mbar. Substrate tubes, obtained by cutting the tubular strand to the desired length, serve as semi-finished products for the manufacture of preforms for optical fibers.

Aspects of the embodiments include an optical fiber formed in a low gravity environment. The optical fiber can be used in airframe applications for missile defense, oil-field applications for down-well laser applications, optical communications, and other applications. The optical fiber can include a fluoride composition, such ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN), and can be characterized by an insertion loss in a range from 13 dB/1000 km to 120 dB/1000 km. The optical fiber can deliver optical energy with low insertion loss at the desired power and wavelength for the various applications.

An optical fiber manufacturing method includes supplying power to a drawing furnace to cause T/V to decrease to T.sub.target/V.sub.target along a quadratic function having a value of the T.sub.target/V.sub.target at an apex with lapse of time, where T is a tension applied to an optical fiber when an optical fiber preform is heated by the drawing furnace and the optical fiber is drawn, V is speed of withdrawing the optical fiber when the optical fiber is heated by the drawing furnace and the optical fiber is drawn, T.sub.target is a target value of the tension, and V.sub.target is a target value of the speed.

A preform material including a starter tip to facilitate an initial fiber draw from the preform within a furnace, wherein the tip comprises a vacuum-sealed tip to receive a plastic grip which attached to an end of a preform.

The core region of an optical fiber is doped with chlorine in a concentration that allows for the viscosity of the core region to be lowered, approaching the viscosity of the surrounding cladding. An annular interface region is disposed between the core and cladding and contains a concentration of fluorine dopant sufficient to match the viscosity of the core. By including this annular stress accommodation region, the cladding layer can be formed to include the relatively high concentration of fluorine required to provide the desired degree of optical signal confinement (i.e., forming a low loss optical fiber). The inclusion of the annular stress accommodation region allows for the formation of a large effective area optical fiber that exhibits low loss (i.e., <0.19 dB/km) in both the C-band and L-band transmission ranges.

A sensor system to provide data for use to control manufacture of an optical fiber in microgravity including a diameter sensor to monitor a diameter of a fiber drawn from a preform material, a tension sensor to monitor tension of the fiber as the fiber is pulled from the preform material to a storage device and a controller in communication with at least one of the diameter sensor and the tension sensor to evaluate sensor data to determine at least one of a speed and rate at which the fiber is pulled from the preform material.

A system for controlling an ambient microgravity environment of a system for drawing optical fiber including a filter arranged to cleanse an environment from contaminants, a molecular sieve arranged in a series of at least one of meshes and baffles to dehumidify the environment, at least one of a pump and a fan to draw an environmental gas through the filter, through the molecular sieve and back in to an ambient environment and a housing in which the filter, molecular sieve and at least one of pump and fan reside.