At+t Corp.

At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Lucent Technologies Inc.

John T Krause

Sandra Greenberg Kosinski

Guenther Wilhelm Kammlott

Richard S Riggs

Edwin Arthur Chandross

Kenneth L Walker

William Alfred Reed

Leonard G Cohen

Charles R Kurkjian

Dimitrios Stroumbakis

Un-Chul Paek

The disclosed method of fusion splicing silica-based optical fiber comprises removing of the polymer coating from the end portions of the respective fibers by contacting the end portions with a chemical polymer remover (e.q., hot sulfuric acid with 5% nitric acid) such that a film of material that comprises the remover remains on the stripped fiber. Typically this is accomplished by refraining from the conventional rinsing of the stripped fiber portions. The film-covered stripped fibers are then fusion spliced in conventional fashion. Splices of strength close to the strength of as-drawn fiber were obtained by this method.

Method of fusion-splicing optical fiber

We have discovered that the strength of arc fusion splices in optical fiber can be adversely affected by particles (e.g., SiO.sub.2 particles) from the electrodes. Disclosed is a method of arc fusion splicing that can substantially increase the probability that a given fiber splice will meet a given strength requirement. The method comprises initiating the arc in a 'cleaning' position selected such that the probability of incidence on the fibers of particles from the electrodes is relatively low, followed by changing the relative position between the electrodes with the arc therebetween and the fibers to the conventional 'heating' position and forming the splice.

Method and apparatus for fusion splicing optical fibers

Fusion splicing of optical fiber generally requires removal of a polymer coating from the end portions of two lengths of fiber. A conventional removal method involves immersion of the fiber ends in an appropriate polymer stripping liquid, e.g., in hot, concentrated sulfuric acid. It is known that the strength of fusion splices generally is statistically distributed, such that there exists a probability that a given splice will pass at a given proof test level. We have found that the splice strength distribution can be shifted towards higher strength if the polymer stripping liquid comprises means for insuring that the liquid is essentially free of strength-reducing particles. Preferred means are concentrated nitric acid. Exemplarily, the liquid is at a temperature in the range 170.degree.-200.degree. C. and comprises concentrated (about 95%) sulfuric acid and about 5% b.v. concentrated (about 70%) nitric acid.

Method of making an optical fiber communication system

Disclosed is an optical communication system comprising at least two optical fibers of dissimilar core sizes, joined by a fusion splice. In one embodiment, the larger-core fiber is a communication fiber, and the smaller-core fiber is an erbium-doped amplifier fiber. A taper region is included adjacent the splice. The diameter of the smaller-core fiber increases within the taper region as the splice is approached along the smaller-core fiber. The taper region is substantially free of constrictions. As a consequence of the taper region, the optical losses associated with the splice are relatively low, even when there is relatively high mismatch between the mode field diameters (at a signal wavelength) in the respective fibers.

Optical communication system comprising a fiber amplifier

In the interest of producing high-strength splice connections between silica-based glass fibers a method of using a tri-particle flow of gases for flame fusion is disclosed. An outer relatively high-velocity flow of oxygen surrounds an intermediate, lower-velocity flow of chlorine or oxygen which in turn surrounds a central flow of H.sub.2, D.sub.2, NH.sub.3, or ND.sub.3. Particularly high strengths are achieved when a central flow of hydrogen or deuterium and an intermediate flow of chlorine are used in such a fashion as to heat fiber ends to be spliced to temperatures of 500 degrees C. and beyond only after these ends have been enveloped by chlorine.

Method for glass fiber splicing by flame fusion

In the interest of reducing the effect on tensile strength of flame processing of a silica-based optical fiber waveguide, such processing is by a method in which a significant flow of oxygen surrounds a flame produced by combustion of hydrogen, deuterium, ammonia, or deuterated ammonia. Flame processing may be for purposes such as, e.g., fiber drawing, fiber fusing for the sake of lateral coupling, refractive index modification by the diffusion of dopants, and fiber splicing in the manufacture of long lengths of fiber. Even though there is no use of chlorine, at least 80 percent of spliced fibers have a tensile strength greater than or equal to 500 kpsi (3.45 GPa) as is desirable in optical fiber cable manufacture.

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New Providence, NJ, United States of America

John T Krause