Things You Should Know About Fiber Optic Splicing

With the wide application of fiber optic technology, fiber optical cables cover more and more areas. So the requirement for long fiber optic cables turn to be higher. As fiber optic cables are generally manufactured in lengths up to about 5 km, when lengths of 10 km are required, for example, what can we do to meet this demand? Splicing is one of the methods. Today, this article will introduce a technology—fiber optic splicing.

What is fiber optic splicing?

Simply put, fiber optic splicing is to joint two fiber optic cables together. Its purpose is to meet the length requirement in cabling systems, and it just causes lower light loss and back reflection than termination, making it the preferred way when the cable runs are too long for a single length of fiber or when joining two different types of cable together, such as a 48-fiber cable to four 12-fiber cables. Splicing is also widely used to restore fiber optic cables when a buried cable is accidentally severed.

Generally, there are two classifications of fiber optic splicing: fusion splicing and mechanical splicing. Here is a brief overview of them.

Fusion Splicing

Fusion splicing is to joint two optical fibers core end-to-end using heat. The source of heat is usually an electric arc, but can also be a laser, or a gas flame, or a tungsten filament through which current is passed. This type of splicing requires specialized equipment to perform the procurement. Fusion splicing offers a lower level of loss and a high degree of permanence. However, it requires the use of the expensive fusion splicing equipment.

Mechanical Splicing

The mechanical splice is often used when connections have to be achieved quickly. Mechanical splices are simply alignment devices, designed to hold the two fiber ends in a precisely aligned position thus enabling light to pass from one fiber into the other. And they are generally applied in semi-permanent connections, for example, in an emergency restoration or for testing and troubleshooting. The loss and reflection in mechanical splicing are greater than that in fusion splicing.

Steps of Fiber Optic Splicing

As mentioned above, there are two different types of splices. Now I’d like to introduce the basic steps of them.

Steps of Fusion Splicing

Step 1. Preparing the fiber. Strip the protective coatings, jackets, tubes, strength members, etc. leaving only the bare fiber showing. During these processes, the main concern is to keep the bare fibers clean. If necessary, clean the fibers with alcohol properly.

Step 2. Cleave the fiber. Here a good fiber cleaver is essential to a successful fusion splice. The cleaved end must be mirror-smooth and perpendicular to the fiber axis to achieve a proper splice.

Step 3. Fuse the fiber. The first thing you need to do is to align the fibers, which can be automatic or manual depending on what equipment you use. Then uses an electrical arc to melt the fibers, permanently welding the two fiber ends together.

Step 4. Protect the fiber. Protecting the fiber from bending and tensile forces will ensure the splice not break during routine handling. A typical fusion splice has a tensile strength between 0.5 and 1.5 lbs and will not break during normal handling but it still requires protection from excessive bending and pulling forces. Using heat shrink tubing, silicone gel and/or mechanical crimp protectors will keep the splice protected from outside elements and breakage.

Steps of Mechanical Splicing

Step 1. Preparing the fiber. Strip the protective layers outside the fiber cores. And also pay attention to keep the bare fibers clean.

Step 2. Cleave the fiber. The process is the same as the cleaving for fusion splicing but the cleave precision is not as critical.

Step 3. Mechanically join the fibers. As the name implies, there is no heat throughout in this joining process. Simply position the fiber ends together inside the mechanical splice unit. The index matching gel inside the mechanical splice apparatus will help couple the light from one fiber end to the other.

Step 4. Protect the fiber. There is no need to add additional protector, for the completed mechanical splice provides its own protection for the splice.

Tips for Fiber Optic Splicing

Point 1. Keep fibers and splicing tools clean thoroughly and frequently. Small particles that cannot be seen with the naked eye could cause tremendous problems when working with fibers. “Excessive” cleaning of your fiber and tools will help you avoid lots of troubles.

Point 2. Properly maintain and operate your cleaver. The cleaver is your most valuable tool in fiber splicing. Within mechanical splicing, you need the proper angle to insure proper end faces or too much light escaping into the air gaps between the two fibers will occur. The index matching gel will eliminate most of the light escape but cannot overcome a low quality cleave.

Point 3. If you use a laser as heat sources, do not look directly into the path of it. And you need to wear eye protection, for laser may hurt your eyes.

Conclusion

As the application of fiber optic cables proliferates, fiber optic splicing is becoming more and more common. Knowledge of fiber optic splicing methods is vital to any company or fiber optic technician involved in Telecommunications or LAN (Local Area Network) and networking projects. Now, do you know more about fiber optic splicing?