Let's imagine that our network requires a long link that a cable coil cannot provide, or that a link is affected and the fiber optic cable breaks, or... what if we need to create a branch? When this happens, we must make a connection between fiber and fiber; this process is called splicing, yes, just like splicing an electrical cable, except that with fiber, greater precision and specialized equipment are required to achieve it.
Fusion splicing is done by "welding" optical fibers; it consists of permanently joining the fibers. It requires a piece of equipment called a fusion splicer, which will have two electrodes responsible for forming an electric arc to melt and join the fiber. The average loss or attenuation ranges from 0.1 to 0.5 dB.
To carry out this process, several materials are needed, as shown in figure 2.
Figure 1. Elements for fusion splicing
To perform a fusion splice, follow these steps:
1. Prepare the optical fiber by removing its coating and cladding with stripping tools.
2. Clean the freshly stripped fiber with a wipe soaked in isopropyl alcohol.
3. Cleave the "bare" optical fiber with a precision cleaver.
4. Carefully transfer the cleaved fiber to the splicer, avoiding bumps or touches.
5. Insert the splice sleeve onto the remaining end and perform the same preparation, cleaning, and cleaving procedure for the fiber.
6. Once the splicer has joined the fiber, place the heat-shrink sleeve to cover the splice.
7. Place the sleeve in the splicer's oven and wait for it to shrink. The splice is now ready.
Mechanical Splice.
This type of splice is made using a device of the same name, which aligns the fibers and holds them together with an index-matching gel or adhesive. This splice is quick to perform and does not require much equipment, however, the attenuation in the link is significant, as it can reach up to 1 dB, so it is recommended for restorations. Unlike fusion splicing, mechanical splicing is not a permanent connection since the fibers are not completely joined; the only goal here is to bring both fibers as close as possible.
Figure 2. Mechanical splice
To perform a mechanical splice, the same tools as for a fusion splice are used, but without the splicer or heat-shrink sleeves.
Figure 3. Mechanical splice kit
The splicing procedure is the same as for fusion splicing up to step 3, then we must do the following:
1. Strip, clean, and cleave the optical fiber (the same preparation steps as in fusion splicing that we saw previously).
2. Insert both ends into the mechanical splice.
3. Close the splice, and pressure clips push the fibers together.
To protect our splices, splice closures are used. Check our next entry to learn more about this topic.
