The act of joining two individual lengths of optical fiber to create a secure connection is called splicing. There are currently two common splicing methods that can be utilized - fusion splicing and mechanical splicing. While both processes share similar initial steps, the differ substantially thereafter in terms of the approach and necessary materials, while producing different results.

With this being the case, how might one choose which path to take? Is one method considered better than the other? In this brief article, we take a closer look at both the fusion and mechanical splicing methods to provide some clarity on the subject. At the conclusion, you should have better idea about how each method works, the benefits and drawbacks of each, and which uses cases or applications are more suited to one or the other.

 
Figure 1: Fusion Splicer machine close-up

Defining Mechanical & Fusion Splicing

The ultimate goal of cable splicing is to create a secure connection between two or more sections of fiber in a way that allows the optical signal to pass through with minimal loss. As we mentioned already, both mechanical and fusion splicing achieve this goal, but they do so in very different ways.

Fusion Splicing

Fusion splicing involves heating the ends of each fiber that are being joined and fusing them together permanently. Because this process requires near-perfect alignment of the fibers and their respective cores, along with fusing the glass together in a precise manner, this is accomplished using a fusion splicer device. The device effectively aligns the two fiber ends, melts the glass via an electric arc, then fuses them together. Because of the resulting splice point in the length of fiber, either a heat-shrinkable protective splice sleeve or a coating material is typically placed over the splice point to give the splice more strength and durability.

Mechanical Splicing

The primary way that mechanical splicing differs from fusion splicing is that it is a manual process that does not permanently fuse or join the fibers together, instead it locks and aligns the fiber ends together with a screw mechanism in a splice case. This method requires no heat or electricity and is performed manually by a technician using the required tools and components.

Fusion Splicing Steps - A Quick Overview

For both fusion and mechanical splicing techniques, there are four distinct steps to the process. The first two steps for each are virtually identical which are covered in this section, but the final two are where the differences come into play.

Fusion Splicing and Mechanical Splicing Step 1 - Fiber / Cable Preparation

To prepare the end of a fiber cable for splicing, a few inches of the protective jacketing, buffer tubing, and coating must be stripped away in order to access the bare glass fiber. After using a handheld stripping tool to remove these layers, the bare fiber is now accessible, which should then be cleaned quickly with an alcoholic wipe to remove any dirt or dust.

Fusion Splicing and Mechanical Splicing Step 2 - Cleaving

Once the bare fiber is prepared, the next step involves cleaving the end fiber, which shouldn’t be confused with cutting. Cleaving is when the fiber is lightly scored with a sharp blade and then flexed until it naturally breaks. To create an ideal connection point for a fusion or a mechanical splice, a clean and smooth cleave that is perpendicular to the fiber is absolutely necessary. The example image below shows examples of poor cleaves on the left and good cleaves on the right:

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When fiber optic field technicians need to test the integrity of a fiber optic cable, they use an Optical Time Domain Reflectometer (OTDR) device that identifies and pinpoints issues like breaks/faults and poor splices, while also certifying the cable length.  To find and resolve issues in the fiber cable quickly and efficiently, it’s critical that they not only have a reliable OTDR device, but just as importantly know how to use it properly in terms of selecting the necessary settings and interpreting the results correctly.  This is achieved by receiving thorough training in the classroom prior to heading out into the field.

Radiation hardened fibers are designed to handle applications and environments where there is greater exposure to radiation and the need for reliable data transmission in those settings. Circumstances where the potential of high levels of radiation exist include nuclear power plants or other nuclear-powered apparatus such as submarines, along with space applications, and high energy physics facilities. Optical fiber plays a critical role in each of these environments providing data transmission, gyroscopes, temperature sensing or diagnostics.

Communications engineers face many complicated decisions when selecting the most appropriate type of fiber optic cabling for their specific needs. Should the fiber be single mode or multimode? If it is multimode, should it be step index fiber or graded index? Those are just two of the multitude of questions that need to be answered when selecting the best fiber solution.

In today’s advanced fiber optic networks, multi-fiber cabling is utilized both inside data centers and across vast field networks as it provides the most efficient approach for deploying large counts of fibers using as little physical space as possible.  At the most basic level, a multi-fiber cable is typically comprised of a ribbon cable surrounded by a protective outer jacketing.  These ribbon and/or multi-fiber cables are available with number options when it comes to fiber counts (ex: 8, 12, 24, etc)

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When utilizing optical fibers for high-speed communications applications, there two primary categories that fibers are grouped into, based on their construction and intended applications. In this article, we will review both Single Mode and Multimode optical fiber classifications, providing a quick introduction to both types and their key differences.

What is Wavelength Division Multiplexing (WDM)?

WDM is a technology approach that allows for the combining ("mux") of multiple individual light wavelengths (signals/channels) from multiple lasers on a single fiber using a passive component for transmission to another location. At that receiving location, WDM components then work in the reverse, demultiplexing ("demux") the combined wavelengths back into individual signals and routed to their respective receivers.