Optical waveguides – With splice
Reexamination Certificate
1998-12-11
2001-04-17
Font, Frank G. (Department: 2877)
Optical waveguides
With splice
C385S031000, C385S088000, C385S089000, C385S090000, C385S091000, C385S092000, C385S093000, C385S094000, C385S095000, C385S096000, C385S097000, C385S098000, C385S099000, C385S114000, C385S136000, C385S137000, C156S158000
Reexamination Certificate
active
06217233
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a restoration method and apparatus for quickly and effectively performing “field” splices on optical fiber.
Quick restoration of optical signal paths is essential when failures occur in an optical fiber network. The failures ranges from cable breaks due to contractor “dig ups” to environmental damage (such as lightning strikes and cable burn). To repair these types of failures, a communication field technician must find and isolate the damaged section of fiber cable, dig up the cable, and splice the fibers back together. Restoration splicing consists of using a quick, temporary splice that will optically couple the cut fiber back together. The most critical characteristic of an optical fiber splice is its insertion loss, that is, the signal loss due to misalignment of the fibers. The misalignment may be along the optical axes between the fibers, or the misalignment may result from too large of a transverse separation between the ends of the fibers. There exist in the art may different type of connector blocks including V-groove channels for locating the fibers prior to splicing. The V-groove channels address the axial misalignment alignment problem, but cannot improve insertion loss related to improper spacing between fiber endfaces. Index matching mediums (gels) may be used to improve the coupling between fiber ends. Oftentimes, however, the gel has bubbles, contaminants or other discontinuities that tend to migrate during the splice operation, and thereafter with temperature cycling. Such migration of the gel and microbubbles can detrimentally affect the splice quality. It would, therefore, be desirable and advantageous to provide a splice element that would eliminate the need to use index matching gel between the fiber endfaces.
SUMMARY OF THE INVENTION
The need remaining in the prior art is addressed by the present invention, which relates to a restoration method and apparatus for quickly and effectively performing “field” splices on optical fiber.
In accordance with the present invention, a transparent splice block is utilized, the block including carefully milled openings for insertion (through either end) of the bare optical fibers. In order to allow for the required “butt-to-butt” coupling of the fiber endfaces, a brightly-colored stripe is disposed on the underside of the splice opening. In operation, the bare fibers inserted through either end of the opening and pushed inward toward each other until the bright color is no longer visible—indicating that the endfaces of the fibers have come into contact.
In a preferred embodiment, the transparent splice block comprises a glass material with the fiber opening milled through the center thereof. For conventional optical fibers, the opening is milled to accept 250 micron fibers, with a bare fiber diameter of 125 microns. In an exemplary arrangement, a bright red stripe may be disposed on the underside of the splice opening to be used as an indicator that the fiber endfaces have come into contact.
Various other arrangements of the present invention will become apparent during the course of the following discussion and by reference to the accompanying drawings.
REFERENCES:
patent: 4717233 (1988-01-01), Skaradnik
patent: 4919510 (1990-04-01), Hoke et al.
patent: 5189717 (1993-02-01), Larson et al.
patent: 5351331 (1994-09-01), Chun et al.
patent: 5896481 (1999-04-01), Beranek et al.
Eslambolchi Hossein
Huffman John Sinclair
Sims Ronald L.
AT&T Corporation
Font Frank G.
Mooney Michael P.
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