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How to Fusion Splice Fiber Optic Cable

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

  1. Fiber Strippers
  2. Kevlar Cutter
  3. Splice Sleeves
  4. Alcohol Wipes
  5. Fiber Optic Cleaver
  6. Microscope (Not mandatory, but very useful for checking fiber ends)
  7. Fusion Splicer

 


 

Step 1: Stripping the Fibers

 

Stripping FiberIt 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 Again

 

Cleave CableKeeping 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

 

Fusion SplicingIt 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.

Need a Fusion Splicer? Check out the FS-8993 Core Alignment Fusion Splicer Kit.

A Quick Guide to Fiber Optic Connectors

You're about to begin a brand new fiber optic installation, or perhaps you're working on an existing one? You'll need a a good idea of what type of connectors will work best. This simple guide should help you in understanding the various fiber optic connectors on the market and get you up and running in no time. Please note that there are many, many types of connectors and variants available, we will only be covering the most commonly used ones here.

LC Connector
LC Connector

 

LC connectors are licensed by Lucent Technologies, now known as Alcatel-Lucent. These connectors are ideal for use in high-density applications due to their small size and feature a pull-proof design. They are available in both simplex and duplex versions with a 1.25mm zirconia ferrule. Additionally LC connectors also make use of an specialized latch mechanism in order to provide stability within rack mounts.

 


 

SC Connector
SC Connector

 

SC connectors, also known as Subscriber Connectors, Square Connectors or Standard Connectors are non-optical disconnect connectors with a 2.5mm pre-radius-ed zirconia ferrule. They are ideal for quick patching of cables into rack or wall mounts due to their push-pull design. Available in simplex and duplex with a reusable duplex holding clip to allow for duplex connections.

 


 

FC Connector
FC Connector

 

FC connectors are known as both Ferrule Connectors and Fiber Channel Connectors. They feature a durable threaded coupling and are best suited for use within telecoms applications and make use of non-optical disconnect.

 

 


 

ST Connector
ST Connector

 

ST connectors or Straight Tip connectors make use of a semi-unique bayonet connection with a 2.5mm ferrule. ST’s are great fiber optic connectors for field installation due to their reliability and durability. They are available in both simplex and and duplex

 

 


 

MTP Connector
MTP / MPO Connector

 

MTP Fiber Connector or Multiple-Fiber Termination Push-On/Pull-off is a brand name for a connector developed by US CONEC® and is an improved high performance version of an MPO Connector. MTP connectors are compatible with MPO connectors. The most common MTP connectors contain 12 fibers but can go up to 24 fibers in newer designs.

MTP is specifically designed for multi-fiber ribbon cables and the typical insertion loss is 0.25db, which is inline with standard SC and ST connectors. The UPC design makes use of a flat surface and the APC variant has an 8° angle in order to minimize back reflection. The connectors are available in Male (Pins) and Female (No Pins) versions.

 


 

MTRJ Connector
MT-RJ Connector

 

MT-RJ Connector stands for Mechanical Transfer Registered Jack or Media Termination – Recommended Jack. MT-RJ connectors are designed to snap into Ethernet ports of various devices such as computers and routers in order to supply networks with fiber optic data transfer speeds.They are typically designed for multimode optic fibers but are available for single-mode as well. They are 2.45mm x 4.4mm in size.

 

With some luck, this guide has helped clear up a few things. However if you’re still not sure which fiber optic connectors are right for you, or perhaps you’d like some more information you can always get in touch with Fibertronics either by phone (877) 320 3143 or email sales@fibertronics.com.

Single mode vs Multimode, What's the Difference?

So you’re sitting there and wondering to yourself, Single-mode, Multimode. What’s the difference? Well wonder no more the answer you’re looking for is just below, but first let’s briefly discuss fiber optics in general.

Fiber optics is essentially sending signals in the form of light, down very thin strands of glass or plastic. The light is sent down the center of the fiber known as the core. The core is encased in an optical material called “cladding”. The cladding ensures the light remains trapped within the core by making use of an optical technique known as “Total Internal Reflection“. Both the core and the cladding are generally made of ultra-pure glass. The cable is then covered and protected by and outer plastic cover called a “jacket”. Jackets come in various types and colors as well but this is a topic for future article.


 

Single-mode Fiber Optic Cable

 

Single-mode cables feature a core with a very small diameter that only allows one mode of light through (thus the term Single-mode). As a result of this the number of reflections resulting from the light traveling down the core are dramatically reduced. This in turn lowers the attenuation and allows the signal to travel both faster and further. If it helps, think of it in terms of a lot of water flowing through a very thin hose pipe, it will be far more compressed, travel faster and further through small the hose than through a large one.

SIngle mode Cable


Single-mode fiber cable is usually identifiable by a standard yellow jacket and available in a typical 9/125 ratio, this means the core has a diameter of 9µm (microns) and the cladding has diameter of 125µm.


 

Multimode Fiber Optic Cable

 

Multimode fiber optic cables sport a larger diameter core that allows multiple modes of light to propagate, simple right? Well not quite, as you would expect due to the larger core diameter more data is able to be transmitted. However, far more light refraction and attenuation takes place. This means that they are generally used over far shorter distances thaningle-mode cables due to signal degradation. They are most commonly found in short distance data applications such as LANs (Local Area Networks).

multimode cable

Multimode fiber is typically available in both 50/125 and 62.5/125 ratios. That is a core to cladding ratio of 50µm to 125µm and 62.5µm to 125µm.

While this is a somewhat simplistic break down of the differences, hopefully you have found it useful in understanding the basic differences between Single-mode cables and Multimode cables and can use this to help you decide which type of cable will best suit your fiber optic cable needs.

How Do Fiber Optics Work?

These days fiber optic cables are used everywhere to connect our modern world and are able to send information across countries and vast oceans, but how do they work? Before we get too stuck in to the more technical stuff, why not check out the video below for a nice, simple summary of how it all comes together. 

How They Work

 

Fiber optics are fairly simple to understand on a basic level. Essentially information in the form of light is sent from one place to another, this is generally done through fiber optic cable. The beauty of this comes from something known as Total Internal Reflection (TIR), what this means is that the light is able to be sent through a flexible fiber optic cable by simply ‘bouncing from one surface to another’ until it reaches it’s destination.

Internal Reflection Diagram
 

Reflection vs Refraction

 

Any time light strikes a surface it can either be reflected from it (reflection) or pass through it (refraction). The key to transmission of light via fiber optics is to ensure that light hits the surface greater than the critical angle to ensure complete reflection and not refraction. This requires quite a bit of mathematics, but to simplify it one should ensure that the angle of the surface the light hits is not too great so as to ensure reflection takes place and not refraction.
 

Understanding the Structure of Fiber Optic Cable

 

Fiber optic cable typically contains a core made of ultra-pure glass which is then surrounded by an outside layer of glass known as cladding. The cladding is designed manufactured in such a way as to decrease it’s index of refraction by using small bits of boron or germanium. The core and cladding are manufactured as a very long, thin piece of glass that is made by heating what is know as a preform with the center being the pure glass core and the outside is the cladding. It is then stretched to an length of unusually around 18.2 m (60 ft).

Single mode Diagram

Sending Data by Light

 

Data is sent and received in our modern society in what is known as binary numbers, essentially 1’s and 0’s. Think of it as a light switch with 2 settings, either On (1) or Off (0). If you turn the light on and off at the switch with a specific pattern it can be used to form somewhat complex messages. Such as the example one below:

Binary Hello

Data is sent similarly through fiber optic cable in the form of laser light pulses using what is known as Pulse Code Modulation or PCM. Unfortunately this is a lengthy topic which maybe discussed in a future article.

In Summary

 

Fiber optics allows us to send information across the globe at the speed of light (186,000 miles per second ) via specifically designed fiber optic cables by making clever use of light reflection and refraction.