Fiber Optic Cable Splicing

Two optical fiber splicing methods are available for permanent joining of two optical fibers. Both methods provide much lower insertion loss compared to fiber connectors.

1. Fiber optic cable fusion splicing – Insertion loss < 0.1dB
2. Fiber mechanical splicing – Insertion loss < 0.5dB

Fiber optic cable fusion splicing

Fiber optic cable fusion splicing provides the lowest-loss connection. Special equipment called fusion splicer is used to perform the fiber fusion splicing. The fusion splicer performs optical fiber fusion splicing in two steps.

1. Precisely align the two fibers
2. Generate a small electric arc to melt the fibers and weld them together

High precision fusion splicers are usually bulky and expensive. With proper training, a fiber splicing technician can routinely achieve less than 0.1dB insertion loss splicing for both single mode and multimode fiber cables.

Fiber optic cable splicing procedure (How to splice fiber optic cable)

1. Strip fiber cable jacket. Strip back about 3 meters of fiber cable jacket to expose the fiber loose tubes or tight buffered fibers. Use cable rip cord to cut through the fiber jacket. Then carefully peel back the jacket and expose the insides. Cut off the excess jacket. Clean off all cable gel with cable gel remover. Separate the fiber loose tubes and buffers by carefully cutting away any yarn or sheath. Leave enough of the strength member to properly secure the cable in the splice enclose.
2. Strip fiber tubes. For a loose tube fiber cable, strip away about 2 meters of fiber tube using a buffer tube stripper and expose the individual fibers.
3. Clean cable gel. Carefully clean all fibers in the loose tube of any filling gel with cable gel remover.
4. Secure cable tubes. Secure the end of the loose tube to the splice tray and lay out cleaned and separated fibers on the table. Strip and clean the other cable tube’s fiber that is to be spliced, and secure to the splice tray.
5. Strip first splicing fiber. Hold the first splicing fiber and remove the 250um fiber coating to expose 5cm of 125um bare fiber cladding with fiber coating stripper tool. For tight buffered fibers, remove 5cm of 900um tight buffer first with a buffer stripping tool, and then remove the 5cm of 250um coating.
6. Place the fusion splice protection sleeve. Put a fusion splice protection sleeve onto the fiber being spliced.
7. Clean the bare fiber. Carefully clean the stripped bare fiber with lint-free wipes soaked in isopropyl alcohol. After cleaning, prevent the fiber from touching anything.
8. Fiber cleaving. With a high precision fiber cleaver, cleave the fiber to a specified length according to your fusion splicer’s manual.
9. Prepare second fiber being spliced. Strip, clean and cleave the other fiber to be spliced.
10. Fusion splicing. Place both fibers in the fusion splicer and do the fusion splice according to its manual.
11. Heat shrink the fusion splice protection sleeve. Slide the fusion splice protection sleeve on the joint and put it into the heat shrink oven, and press the heat button.
12. Place splice into splice tray. Carefully place the finished splice into the splice tray and loop excess fiber around its guides. Ensure that the fiber’s minimum bending radius is not compromised.
13. Perform OTDR test. Perform a OTDR test of the splice and redo the splice if necessary.
14. Close the splice tray. After all fibers have been spliced, carefully close the splice tray and place it into the splice enclosure.
15. Bidirectional OTDR test (or power meter test). Test the splices with an OTDR or power meter from both directions.
16. Mount the splice enclosure.  Close and mount the splice enclosure if all splices meet the specifications.

Fiber optic cable mechanical splices

Fiber optic cable mechanical splicing is an alternate splicing technique which does not require a fusion splicer.

Mechanical splicing uses a small, mechanical splice, about 6cm long and 1cm in diameter that permanently joins the two optical fibers.

A mechanical splice is a small fiber connector that precisely aligns two bare fibers and then secures them mechanically.

A snap-type cover, an adhesive cover, or both, are used to permanently fasten the splice.

Fiber optic cable mechanical splices are small, quite easy to use, and are very handy for either quick repairs or permanent installations. They are available in permanent and reenterable types.

Fiber optic cable mechanical splices are available for single mode or multimode fibers. Their connection loss are usually less than 0.5dB which is much bigger than a 0.1dB fusion splice.