Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/255—Splicing of light guides, e.g. by fusion or bonding
  • G02B6/2551—Splicing of light guides, e.g. by fusion or bonding using thermal methods, e.g. fusion welding by arc discharge, laser beam, plasma torch

Definitions

• the invention is concerned with connecting glass fibers and, more particularly, with producing high-strength splice connections of lightguide glass fibers by heat fusion.
• Lightwave communications via lightguide glass fibers is widely considered as virtually certain to replace most of current electrical communications over copper wire, and the manufacture of optical fibers has reached a high level of perfection. Fabrication aspects such as the making of preforms, the drawing of fibers, their coating and sheathing, and their interconnection are highly advanced.
• the invention is a method for splicing glass fibers by heat fusion.
• the method involves the use of a tri-partite flow of gases, namely, an outer, relatively high-velocity oxygen flow, an intermediate, lower-velocity chlorine or oxygen flow, and a central flow of H2, D2, H3 or ND3.
• Resulting spliced fibers have a yield strength which is at least 60 percent of pristine strength.
• the Figure is a schematic cross-sectional view of a triple-orifice nozzle of a torch as may be conveniently used to practice the invention. Detailed Description
• the Figure shows central orifice 1 , intermediate orifice 3, and outer orifice 5 of a triple nozzle having coaxial cylindrical nozzles 2, 4, and 6.
• Each of the orifices 1, 3, and 5 can be connected to a gas supply to produce a corresponding flow out of each respective orifice.
• the outer diameter of the outermost nozzle 6 is typically of the order of 0.5 centimeter.
• the invention is aimed at producing high-strengt splice connections between glass fibers, as are being used, e.g., in optical communications.
• Such fibers have a surface glass portion which preferably comprises at least 95 weight percent silica, and their diameter is of the order of 100 micrometers.
• Optical fibers typically comprise a core portion having a refractive index which is slightly greater than the refractive index of a surrounding claddi-ng portion; in the case of fibers for th transmission of a single optical mode the diameter of the core portion may be of the order of 10 micrometers. Raise refractive index of a core portion is conveniently achieve by doping such as, e.g., by the addition of germanium to silica.
• Processing in accordance with the invention call for bringing essentially coaxially aligned glass fibers into end-to-end contact and heating in a flame which is produced upon combustion in a flow of gases.
• This flow preferably comprises three portions as produced, e.g., by nozzle as shown in the Figure and as may be designated outer, intermediate, and central portions.
• the outer flow portion preferably is at least 50 volume percent oxygen
• the intermediate flow portion is preferably at least 50 volume percent chlorine, oxygen, or a mixture of chlorine and oxygen
• the central flow portion is preferably at least 50 volume percent hydrogen, ammonia, deuterium, deuterated ammonia, or a mixture thereof.
• a splice connection is produced in accordance with the invention by heating in a flame produced upon combustion in a flow having portions as described above.
• the temperature of fiber ends being joined preferably does not exceed 1800 degrees C or, more favorably, does not exceed 1700 degrees C.
• Temperature control is most readil achieved by regulating flow through the central orifice. Fusion time depends indirectly on fusion temperature and directly on fiber diameter; fusion times in the range of from 15 seconds to 2 minutes are typical.
• Splice connections made in accordance with the invention produce a spliced fiber having a preferred tensile strength which is greater than or equal to 60 percent of pristine fiber strength (the tensile strengt of fibers or the lesser of the tensile strengths of fibers being joined).
• Particularly high strengths of at least 95 percent of pristine strength are achieved when the inne flow is essentially hydrogen or. deuterium and the intermediate flow is essentially chlorine and if care is taken to prevent excessive heating of fiber ends prior to their being inside of the chlorine flow. This is conveniently achieved by initially keeping central hydroge flow at a low rate so that a preferred temperature of 500 degrees C is not exceeded until after fiber ends are within the chlorine flow.
• resulting fiber strengths are greater than or equal to 800 kpsi.
• Example. Two essentially identical single-mode optical fibers were spliced by heat fusing in accordance with the invention. The fibers had Ge-doped cores having a diamete of approximately 10 micrometers and essentially pure silic claddings. Overall fiber diameter was 125 micrometers. The ends of the fibers were placed end-to-end and exposed to a flame produced by a torch having three concentric orifices.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Mechanical Coupling Of Light Guides (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 1985
  • 1985-01-15 EP EP19850900883 patent/EP0169237A1/de active Pending
  • 1985-01-15 JP JP60500581A patent/JPS61501172A/ja active Pending
  • 1985-01-15 DE DE8585300257T patent/DE3562136D1/de not_active Expired
  • 1985-01-15 WO PCT/US1985/000066 patent/WO1985003283A1/en not_active Ceased
  • 1985-01-15 EP EP19850300257 patent/EP0150095B1/de not_active Expired

Non-Patent Citations (1)

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