Bell Telephone Laboratories

At&t Bell Laboratories

William George French

John Burnette MacChesney

G William Tasker

Leonard G Cohen

James W Fleming, Jr

A method is disclosed for making an optical fiber by drawing a preform whose fabrication involves deposition of a glass on a substrate by means of a chemical reaction between gaseous reagents. According to the disclosed method, accurately controlled amounts of a gaseous reagent are produced by flash evaporating a metered flow of a liquid reagent. The disclosed method is of particular interest for the industrial production of optical fibers.

Method for making low-loss optical waveguides on an industrial scale

Optical fibers are produced with improved cross sectional circularity. In the course of the fabrication process, the tubular preform from which the fibers are drawn, is collapsed under positive internal pressure. This removes most cross sectional noncircularities that may have developed during fabrication of the preform, and also ensures the collapse of the preform to a structure with circular cross section.

Fabrication of optical fibers with improved cross sectional circularity

This application discloses a technique for producing optical fibers with longitudinal variations in index of refraction. The deposition apparatus is arranged to allow for the formation of an intertwined double helix of two different materials. The technique does not require imposing any time dependent conditions on the fabrication apparatus.

Optical fibers with helical gradations in composition

A single mode optical transmission line consisting of a core and a clad, both formed from essentially the same type of multicomponent glass, e.g. borosilicate, for use with electromagnetic energy having a wavelength between 0.5.mu.m and 2.0.mu.m. The core has a higher refractive index than the clad because the relative concentrations of the constituents of the glass composition are varied between core and clad, e.g., the ratio of SiO.sub.2 /B.sub.2 O.sub.3 concentrations is higher in the core than in the clad.

Single mode optical transmission line

A method is disclosed for producing optical fibers which are drawn with diameter variations in the transmitting core but with uniform overall diameter. In this process the glass starting member used in fabricating the optical fiber preform is etched with appropriate grooves. Additional glass is subsequently deposited on the etched starting member, and a fiber is drawn from the preform so fabricated.

Method for making optical fibers with variations in core diameter

Method for making optical fibers with helical gradations in composition

A multimode optical fiber waveguide with graded refractive index for lessening modal dispersion with the gradient produced at least in part by radially decreasing boron oxide content outwardly from the core center within a high silica glass core minimizes modal dispersion by use of a non-parabolic grading function. The optimum gradient for a simple binary borosilicate system for a wavelength of from approximately 0.5 to 1.1 micrometers corresponds with .alpha. = 1.77 .+-. 10 percent in the equation n = n.sub.1 [1-2.DELTA.(r/a).sup..alpha.].sup.1/2, in which n.sub.1 is the axial core index r is the distance from the fiber axis, a is the core radius, .DELTA. is the relative index difference between core center and cladding and .alpha. is a power law exponent which characterizes the profile.

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Plainfield, NJ, United States of America

William George French