Fiber optic termination is a necessary step for installing a fiber optic network. It is a physical connection of a fiber optic cable to create a seamless connection between similar or dissimilar devices. And any mistakes that occur in the termination will cause the system to break down or malfunction and raise some problems like return loss or insertion loss. To minimize such losses, the fibers must be aligned and connected as accurately as possible. There are generally two ways how we terminate fiber optic cables: connector or splicing.
Termination by Connectors
Terminating fiber cables by using connectors is a temporary way of termination. Connectors are normally used to make a temporary joint between two fibers or connect the fiber to a piece of network equipment. A fiber connector is composed of four key components: ferrule, connector body and coupling device. The ferrule is a mechanical fixture that is used to align and polish optical fibers, normally made of hardened materials such as ceramic, metal or plastic. The connector body supports the ferrule and sheaths the fibers. The coupling device provides a connection between the connector body and the optical device.
Guide to Fiber Optic Connectors
Most fiber connectors are the plug-and-play type to allow average users to terminate the fiber cables by themselves. Numerous types of connectors have been developed, such as ST, SC and LC, to offer easier termination at a rather lower cost.
• ST connector: The Straight Tip (ST) connector utilizes a bayonet-style socket and has a long cylindrical ferrule to hold the fiber. It is the most popular fiber connector in multi-mode networks. It’s spring-loaded, which means it can be easily inserted and removed.
• SC connector: The subscriber connector, SC connector, is a snap-in connector that latches with a simple push-pull motion. It normally comes with a square plastic housing. It’s mainly designed for the single-mode and duplex networks, often utilized in optical network applications, such as cable TV, media converters and FTTX.
• LC connector: The Lucent Connector is a standard ceramic ferrule connector that can be easily terminated with any adhesive, nearly half the size of the SC connector (smaller ferrule-1.25mm). The LC connector is mainly used for single-mode systems and high-density network applications, like data centers, local networks, FTTH, CATV, etc.
• MU connector: The MU connector is a miniature SC connector with a square shape and push-pull mating mechanism, ideal for both single-mode and multi-mode fibers. It is also applicable to high-density applications like data centers, telecommunications, etc.
How to Terminate Fibers with Connectors
In this section, we’ll walk through all the steps to terminate a fiber cable with a connector in less than 5 minutes. You’ll need to prepare: a cleaver, a striper, a cable clamp, a gauge, Kevlar scissors, cleaning supplies and the connector. Now, follow the procedures below to terminate fibers on your own.
1.First, cut and clean the fiber optic cable before you start. Use the clamp to fix the cable, assemble the connector housing, put the boot on the cable before you start stripping it.
2.Measure the jacket strip length with the gauge, use the stripper to strip off the jacket and cut off the Kevlar fibers with the scissors. Measure the buffer strip length and strip the buffer off at about 1-centimeter segments (1 centimeter at a time) to keep the fiber from bending or breaking. Then use the stripper to slightly clean off the cladding.
3.Insert the fiber strand into the trapdoor of the cleaver, fix it with the clamp and start the cleaver. After a precision cleave, you need to decontaminate the dust, grease or the leftovers of the cladding from the fiber. Use the cleaning supplies (alcohol) to draw the contaminants from the fiber and repeat this step several times until it’s clean.
4.Insert the fiber into the pre-assembled fiber connector until you feel the pressure to make sure it’s connected. Then slightly slide the boot up and tighten the connector. Lastly, remove the cable clamp and you got a finished fiber connector.
Field Termination vs Factory Termination
Connector termination can also be divided into field termination and factory/pre-termination. The field termination is also called on-site termination, in which connectors are added in the field with specialized tools. You can customize the cable length with very little planning time required, but a professional hand might be needed for precise termination. However, factory termination is a more cost-effective and reliable solution to make a quick and precise connection between two fibers. In the factory termination, the fiber optic cable is 100% factory-terminated, tested with a plug-and-play deployment before shipment.
What is a Pre-terminated Fiber Cable?
The per-terminated fiber cable arrives on-site with the connector attached and ready to install. It’s normally made at a pre-determined length, and it’s undeniable of higher quality than its counterpart. The pre-terminate cable helps eliminate rework, transmission testing, etc. And it comes in a plug-and-play design, which can be easily connected and disconnected, cutting off the deployment time by at least 70%. It is manufacured and assembled in a well-controlled environment to ensure the best possible network performance, and signal loss can be highly restrained with thorough inspections. The pre-terminated cable can be used in mission-critical applications that demand the highest level of accuracy, like video surveillance systems .
Termination by Splicing
Splicing is a process to align two fiber strands to the same centerline to create a permanent connection, and it’s only needed when the cable runs are too long for one pull, especially in infield installations. Fiber optic splicing is the most effective way to restore the fiber cable when it’s broken or severed. Splicing requires special tools and the quality largely depends on skill, experience, and components. There are mainly two methods of splicing: fusion splicing and mechanical splicing.
Mechanical Splicing
In mechanical splicing, the fiber optic strands are aligned and fastened with the snap-type covers. It uses a mechanical splice device to join the two fibers together, but the fibers are not permanently connected, just precisely held together to form a centreline via which the light can pass through. There are a number of types of mechanical splices, like glass tubes or V-shaped metal clamps. The mechanical splicing is less costly and it doesn’t require a special tool. It’s usually used for restoration, also available for single-mode and multi-mode fibers, but it’s not as robust as the fusion splicing.
Follow the procedures below for mechanical splicing:
Mechanical splicing is easy to do if you have the tools: a stripper, a cleaver, a mechanical splice and cleaning supplies. Strip the jacket, cladding and other protective layers of the fiber optic cable until you can see the bare fiber. Cleave the fiber to get a clean break and clean it with alcohol to wipe off the finger grease, dust and other contaminants. Insert the cleaved ends of the fibers into the mechanical splice and the index matching gel inside the splice will connect the fibers together.
Fusion Splicing
In fusion splicing, you’ll need a special fusion splicer to fuse the two fiber ends with an electric arc. The connection is more permanent than the mechanical one, and it can produce a non-productive connection, which highly reduces reflection and insertion loss. It is usually used for outdoor, long-haul and high-performance single-mode networks. Additionally, fusion splicing can handle various cable types. But the fusion splicing is more expensive than mechanical splicing. A good fusion splicer will cost you $15,000 to $40,000. And it cannot be done in an explosive atmosphere.
Follow the procedures below for mechanical splicing:
To complete a fusion splice, you will need a fusion splicer, a stripper, a cleaver, heat-shrink protective sleeves and cleaning supplies. First, before you do anything, put the heat-shrink sleeve on both fiber ends to protect the fibers from excessive bending after termination. Use the stripper to remove the coating, clean the fiber with alcohol wipes and use the cleaver to cut off the fiber to achieve a proper splice. Then make sure your fusion splicer is powered up and warmed up before fusing. Align the ends of the fibers within the splicer, and once both fibers are clamped in place, the machine will automatically move the fibers in towards each other. The fibers will be fused by the electric arc and the two fibers are permanently welded.
Manage Fibers with a Fiber Termination Box
Fiber termination box is a distribution box designed for fiber cable management (fiber patch cables/pigtails) to handle large quantities of cables in an orderly manner. The termination box integrates the termination, splicing, storage and management of fiber cables all in one unit, saving time and cost. It provides a protective connection for fiber cables and pigtails, and it has sufficient impact strength, easy to install in different scenarios. There are different types of fiber termination boxes: outdoor and indoor, wall-mounted and rack-mounted, etc.
Fiber termination is an important step in the installation of fiber optic networks. Whether you choose to terminate the fibers with connectors or splicing, make sure you make a precise connection. For more information, please continue to read Tips on Quick Fiber Termination.
