Fusion Splicing is simply joining two optical fibers together by making use of heat. The two optical fibers should be fused in such as way as to allow light to be passed through them without scattering or reflecting light back at the point of the splice. The heat used to fuse the two fibers together is usually in the form of an electric arc, however it can also be achieved using a laser or even gas flame, but these methods are considered dated and inferior . This very simple Fusion Splicing guide should help to explain the process without getting too technical.
What You’ll Need
Fiber Strippers
Kevlar Cutter
Splice Sleeves
Alcohol Wipes
Fiber Optic Cleaver
Microscope (Not mandatory, but very useful for checking fiber ends)
Step 1: Stripping the Fibers
It sounds simple enough right? Unfortunately this is not quite as simple as stripping the simple coating of your average house-hold copper cable. In this case you will first be removing the polymer coating by making use of Fiber Strippers, which are specially designed for stripping the coating off the fiber. Ideally 1 and half inches (40 mm) should be removed from each end of the fiber you are joining. This should be done incrementally and gently while ensuring the stripper is held at a slight angle during the process.
With the coating stripped from the fibers it is now time to simply clip away any excess, exposed Kevlar with your Kevlar cutter. Once completed slide one of your Splice Sleeves onto one of your fiber, you may not be able to do this once you have spliced the two fibers together so it is best to do it now.
Step 2: Clean, Cleave and Clean
Keeping the fibers clean is of the utmost importance when it comes to fusion splicing. It cannot be repeated enough, ensure that the fibers you are working with are cleaned after every major interaction with them. You do this by gently wiping them down with Alcohol Wipes.
Once clean it is time to cleave the fibers. The fiber should ideally be cleaved using what is know as the score-and -break method, this is done to ensure that the end face is perfectly flat and perpendicular to the axis of the fiber. This is best done by making use of a quality Fiber Optic Cleaver. The closer the cleave angle is to 90 degrees on both fibers the better, this will result in less optical loss from the splice. After cleaving both fibers it is time to once again clean the ends with the Alcohol Wipes.
Step 3: Fusion Splicing
It is now time to make use of your Fusion Splicer, begin by placing each fiber into the guides on the Fusion Splicer and clamp them into places securely. Close the lid of the splicer and be sure to select the correct settings on the monitor and program in the correct fiber types into the Fusion Splicer. The fiber ends will be automatically moved into position, at this point a prefuse cycle will begin and any remaining dirt on the fiber ends will be removed as preheating begins. Next the fusion splicer will attempt to align the two fibers by inspecting the cleaves, bad cleaves will result in misalignment and will be rejected. If the cleaves are good the fibers will be fused by an automatic arc cycle that heats the ends and feeds the fibers together at a controlled rate.
Once fusion has been completed the Fusion Splicer will inspect the splice and estimate the total optical loss of the splice. Should it need to be remade it will inform you. If all goes according to plan it is now time to remove the fibers from the guides and move the splice protector over the splice and shrink it to fit (Most splicing machines have a heating device for heat shrinking protective sleeves).
As previously mentioned, this is a very simple guide. There are many variables that must be taken into account when you are splicing different types of fiber. So while it is difficult to get down to specifics hopefully this guide should give you a good idea of the process as a whole and get you started. Just remember to take your time while splicing in order ensure a good clean splice, it will save time in the long run.
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