How to Splice Fiber Optic Cables

How to Splice Fiber Optic Cables
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What is a Fusion Splicer?

A fusion splicer is a machine that aligns and then splices two or more fiber optic cables together using an electric arc. A splicer creates a permanent fusion with minimal loss and reflectance.

Fiber optic cabling is the neural network of modern society, carrying everything from breaking news to funny memes. So, what happens when fiber breaks? Thanks to fiber splicing, that endless flood of data and information doesn't need to stop.

Fiber splicing allows technicians to alter the fragile cables, whether for a repair or regular maintenance. Faulty or downed cables can be fused with a working one to restore functionality.

Limited cable length is another common issue now solved with fiber splicing. Technicians are no longer limited by the short fiber optic cables that can be bought, extending their cables to meet every need with a simple splice.

Fiber optic cables and the data they carry continue to prove critical to our everyday lives. Through fiber splicing, nothing needs to stop that vital flow of data.

What is Fiber Splicing?

Fiber optic splicing is the process of joining two ends of different fiber optic cables and creating one functioning cable. Splicing can prove necessary if a fiber cable is broken and cannot be replaced or if a cable isn't long enough and needs the additional length. When done correctly, fiber splicing causes little insertion loss and reflectance, creating a cable with improved durability.

Fiber optic cabling can require a delicate touch to fix or fit the specific needs of a job. When issues or limitations appear with the cabling, fiber optic splicing offers a flexible solution.

The different fiber splicing methods perform the same function: to repair or alter fiber optic cables. Despite the similar purposes, these procedures can differ greatly, changing costs, time, and effectiveness.

Fiber optic splicing is a procedure to save time and costs in telecommunications installation and maintenance. But it's the method of fiber splicing that can alter results and durability. The two most common methods of cable splicing are mechanical and fusion.

Mechanical Splicing vs. Fusion Splicing

For a simple fix to a multifiber cable, mechanical splicing can prove ideal as it's quick and requires few tools. The fusion splicing procedure requires a state-of-the-art device and other tools. However, this method does produce durable results with almost no loss. There are many factors to consider when choosing mechanical splicing vs. fusion splicing.

Mechanical Splicing

A mechanical splice aligns two or more cleaved fiber tips and keeps the fibers together with an assembly. The connection is protected with a cover, usually a plastic snap-type cover. Mechanical splicing takes much less time and effort, using no power supplies and very few tools. Although, a mechanical splice is often considered temporary and can cause an insertion loss of about 0.3 dB.

Fusion Splicing

Fusion splicing remains the most commonly-used method of fiber optic splicing. Rather than using a cover to align the cables, this method involves fusing the fibers with extreme heat. The permanent fix creates a much more durable connection that can reduce insertion loss to 0.02 dB. Between the durability and improved performance, technicians usually opt to use a fusion splicer when possible.

A fusion splicer in use.

What is Fusion Splicing?

Fusion splicing is a test method that requires aligning fibers from two fiber optic cables and welding the strands, permanently fusing the fiber cores. A fusion splicer or electronic arc is used to weld the cables and create a joint that is non-reflective and maintains an optical signal transmission. Fusion splicing also prevents nearly all insertion loss and attenuation loss.

Fusion splicing is also the most reliable method for single-mode fibers. Different from multimode fibers, single-mode fibers have a thin core that sends signals without touching the fiber's edges. Fusion splicing offers a delicate and precise solution that will maintain the fiber's structure.

What is a Fusion Splicer and How Does it Work?

A fusion splicer is the most efficient tool in fiber splicing. The fusion splicer is an automated machine that both aligns and welds the fibers into one.

The machine uses cameras to align the two fiber ends and removes any dust or particles that prevent a clean fusion. The fusion splicer then provides heat from an electrical arc to weld the ends together. A fiber optic fusion splicer will further test the integrity of the weld, giving a tug to the fiber to ensure that it's stable.

How to Splice Fiber Optic Cables With a Fusion Splicer

An advanced piece of technology, these machines break a complicated process into a handful of simple fusion splicing steps:

  1. Strip the Fibers - Before they can be fused, the user needs to remove the cable jacket and coating from the two fiber optic cables. Using a tool like a mechanical fiber stripper, reduce the coating and exterior until all that's left are bare fiber cores.
  2. Clean the Fibers - Although a fusion splicer will burn off any impurities before the fusion, the user also needs to clean the fibers. Careful applying a fiber optic cleaning solution or isopropyl alcohol should remove most dust or particles.
  3. Cleave the Fibers - This step requires the most precision from the technician. Using a fiber cleaver, carefully create a break within the fiber with ends that are perpendicular to the fiber axis.
  4. Align the Fibers - If using a splicer with automatic alignment, simply place the fiber ends within the device's holder. For splicers with manual alignment, match the fiber end faces so the electrodes are centered.
  5. Fuse the Fibers - Before fusion, most splicers will burn off those harmful particles or moisture. The fusion splicer uses an electric arc to create a spark, melting the fiber ends and fusing them together.
  6. Protect the Fusion Splice - Once the fusion is inspected, make sure the joint is safe. Apply a heat shrink sleeve around the newly fused area.
The process of using a fusion splicer.

Choosing the Right Fiber Optic Fusion Splicer

Just as there are different fiber optic cables, there are many different fusion splicers to handle those cables. Cutting-edge technologies have further created more fusion splicers to meet almost every need. Whether it is a ribbon splicer to handle 16 fibers at once or a cladding alignment fusion splicer to save money, it's critical to choose the right fusion splicer.

Single Fiber Fusion Splicer

Simply splicing one fiber with another, the single fiber fusion splicer has still seen many upgrades in recent years. Most single fiber splicers can now handle fibers as small as 250 microns. The accuracy and precision also translate to a splice loss of only 0.02 dB.

The single fiber fusion splicer also cleaves and applies a protective sleeve with efficiency as most machines handle each task in about 10 seconds. The Fujikura FSM-60S Fusion Splicer is a single-fiber model that delivers a remarkable balance of precision and splicing speed.

Ribbon Fiber Fusion Splicer

When conducting a large number of fusion splices at once, the ribbon fiber models may be the best choice. A ribbon or mass fusion splicer maintains excellent accuracy and precision but conducts many splices at once. Some advanced models can splice up to 16 fiber ribbons simultaneously. When time is the most important factor, a ribbon fiber fusion splicer is likely the best choice. Models like the Sumitomo Quantum Type Q101-M12 Mass Fusion Splicer deliver precise splices with a wide range of 1 to 12 fibers. 

Core Alignment Splicer

The differences in fusion splicing also come down to the alignment. A core alignment splicer does the aligning for the user through a mix of light, cameras, and automated fiber holders. The machine does not perform a splice until perfectly aligning the two fibers by their cores.

The device can also adjust the alignment based on pre-set parameters for the splice. Balancing versatility and precision, a core alignment splicer is best for consistent splicing results. The Fujikura 70S+ Fusion Splicer is a core alignment model that maintains a quick splice time.

Cladding Alignment Splicers

Rather than aligning the core of the fibers, a cladding alignment splicer only requires the outer cladding to align. Matching the cladding on the outside of the fibers can result in lost accuracy when splicing. Although, the cladding alignment splicers will also perform their splices more quickly and cost less than the more precise models. A cladding alignment splicer is an acceptable option for jobs where loss rate is a lower priority.

Fusion Splicing Equipment

ATEC recommends the following products for your fusion splicing and fiber testing applications:
Fusion Splicers

Fusion Splicers

Fiber Testers

Fiber Testers and OTDRs