How Do Fiber Optic Cables Work

Fiber optic cables

Have you ever wondered how the world’s internet, cable television, and telephone systems can transmit data at lightning speed? We’ve compiled all the basic information on optical fiber technology so you get a better understanding of the purpose, features, benefits, and various uses of fiber optic cables.  

It’s usually supported by something called a “Fiber Optic Cable”.

Fiber optic cables have completely revolutionized the world of network communication. Today, these cables have almost wiped out the need for traditional methods of networking using copper wires. 

While most of us have heard the term “fiber optics’ or “optical fiber technology” to describe a type of cable, few of us really understand what it’s really all about. 

We’ve compiled all the basic information on optical fiber technology so you get a better understanding of the purpose, features, benefits, and various uses of fiber optic cables.  

What is Optical Fiber Technology?

A fiber optic cable is a network cable that contains thin strands of carefully drawn glass fiber inside an insulated casing. These strands are arranged in bundles called optical cables and are designed for long-distance, high-performance data networking, and telecommunications. Compared to other wired cables such as copper cables, fiber optic cables have a much larger bandwidth and transmit data at very long distances. 

How does Fiber Optic Cable Transmit Data?

Fiber optic cables consist of dozens to hundreds of optical fibers. These cables transmit data using fast-traveling pulses of light.

Another layer of glass, called “cladding” is another layer of glass wrapped around the central core and causes light to repeatedly bounce off the walls of the cable rather than leak out at the edges, enabling the signal to go farther without attenuation.

Since fiber optics uses light rather than electrical signals to transfer data, fiber-optic cable speed is incredibly fast —very close to the speed of light. 

There are various types of fiber optic cables, most of the time these cables end up in fiber optic cable assemblies to execute a specific function.

The 2 primary types of optical fiber cables are single-mode and multi-mode. Single Mode uses extremely thin glass strands and a laser to generate light, while multimode optical fiber cables use LEDs. 

Advantages of Fiber Optic Cables

Fiber optic cables offer several advantages over long-distance copper cabling

  • Fiber optics have a higher capacity. Their network bandwidth can easily exceed the bandwidth of a copper cable with similar thickness. Standard fiber cables are rated at 10 Gbps, 40 Gbps, and 100 Gbps.
  • The need for signal boosters is no longer necessary as light can travel at a much longer distance.
  • It is less susceptible to interference. A copper network cable needs shielding to protect it from electromagnetic interference whereas fiber optic cables avoid most of these problems. 

Also Read: What Is Fiber Optic Cable and How Does It Work?

Where Are Fiber Optic Cables Used?

Fiber optic cables are now the foundation of our communication and computer networks. 

Here are some of the most popular daily uses of fiber optic cables: 


Fiber optic cables transmit data at very high speeds. This technology is widely used in Internet cables. Fiber optic cables are less bulky, lighter, more flexible, and carry more data. 

Cable TV

The use of fiber optic cables in the transmission of cable signals has grown in recent years. Fiber optic cables are ideal for transmitting signals for high definition televisions due to their larger bandwidth and higher speeds. 


With the use of fiber-optic communication, telephones are now able to connect faster and talk to your friends without any lag on either side.  

Computer Networking 

The use of fiber optic cables has allowed networking between computers in a single building or nearby structures to become much faster. Users of today can experience the difference in the decreased amount of time it takes to transfer files and information across networks. 

Surgery and Dentistry

Fiber optic cables are also useful in the field of medicine and research. Optical communication is an essential part of non-intrusive surgical methods such as endoscopy. They are also used in microscopy and biomedical research.

Lighting and Decorations

In recent years, fiber optic cables have been used as an easy, economical, and attractive option for lighting decorations and even Christmas trees.

Mechanical Checks

In today’s modern times, engineers have used fiber optic cables in checking hard to reach places. A great example of this is pipe inspections that are usually conducted by plumbers.

Military and Space Applications

The field of military and aerospace both require an extremely high level of data security. Fiber optic cables offer an ideal solution to protect data transmission in both areas.

The Automotive Industry 

Fiber optic cables are widely used in the interior and exterior lighting of vehicles. It’s the ability to conserve space, provide superior lighting, and transmit signals between different parts of the vehicle that make it invaluable to the automotive industry.

How Can You Tell If A Cable Is Bad?

If you have a newly installed fiber optic cable that needs fixing, it’s easy to get confused about how to troubleshoot the problem. Here are the common problems usually observed in a bad fiber optic cable.

No Light At All.

This problem is a simple identification problem, where you are not dealing with the same fiber at both ends. Since cables may have many fibers and color-coding, it’s sometimes hard to see two technicians working on each end of the cable, connecting them to different fibers.

The solution to this problem is to use a visible light source or a ‘fiber tracer’ to identify the fiber to be tested next. An inexpensive fiber will pay for itself in no time, as it can also be used as a continuity tester, confirming that the fiber is capable of transmitting light. 

If only one fiber won’t transmit light, it’s probably due to a bad connector. Diagnosing the faulty one can be a problem. Check the fiber at the end of the connector ferrule with a microscope, looking for dirt, cracks in the fiber, or a really bad polish. If both ferrule connectors look OK, the problem is internal.

Unless you have a visual fault locator or OTDR (Optical Time Domain Reflectometer), it might be best to flip a coin to decide which connector to re-terminate first.

Don’t re-terminate both ends, instead use a visual fault locator (VFL) that can help you find the bad connector. It uses a bright-red laser coupled into the fiber. To troubleshoot, plug the suspect connector into the VFL and look at its back. 

If a lot of red light is visible, the connector is bad and should be replaced immediately. If you look from the other end and see light coming only out of the fiber, that indicates a good connector. If the whole ferrule glows, that’s an indication that the fiber may be damaged.

OTDRs can determine the bad connector if the cable is long enough. Use a long launch cable and the shortest pulse width for maximum resolution. Another trick is to connect the far end to a known good fiber, which allows testing both connectors at once.

Can Broken Fiber Optic Cables Be Repaired? 

Fiber optic cables that are installed underground are quite durable. However, there may be instances that it can get damaged or torn due to digging. Fortunately, a fiber optic cable can be repaired if it ever gets torn with the help of a technician.

Here are the steps to take if ever you experience a broken fiber optic cable:

Step 1: Find the tear in your fiber optic cable

A fiber optic technician will usually diagnose the problem by identifying a tear in the fiber optic cable and where it is located by using an optical time-domain reflectometer, or an OTDR. This device is used to send light-pulses through your fiber optic cable and pinpoint the location of the tear. Once identified, they can start digging up the cable at the point of the tear. 

Step 2: Preparing your fiber optic cable for repair

After your fiber optic technician has dug up your fiber optic cable, they can start the process of preparing it for repair. They’ll start by stripping off the jacket that is wrapped around your cable without doing any additional damage to the fibers that sit underneath it.

Step 3: Repairing your fiber optic cable

At this point, your fiber optic technician should be ready to begin repairing your torn fiber optic cable for you. They can do it by using either a fusion splice or a mechanical splice. Either way, they will use a fiber cleaver to trim the damaged ends of your fiber optic cable before carefully splicing them back together.

Step 4: Testing your fiber optic cable and burying it back in the ground

Once a fiber optic technician has successfully repaired your fiber optic cable, they can run some tests on it and see if the fusion splice or mechanical splice was done correctly. Once they diagnose and fix the problem they can bury it back in the ground so that you can start using your fiber optic cable again.

This guide has given all the basic information needed for you to get a basic understanding of how fiber optic cable technology works. With the continued growth of fiber technology, the use of fiber cables has steadily spread across various industries making the lives of humanity much easier.

Due to the complexity of torn fiber optic cables, professionals may need top-quality fiber optic cables for their repairs. If that’s the case, Tevelec, one of the leading wire and cable distributors in the USA and Canada, is a great choice for quality cable and wire solutions. 

Tevelec operates distributing facilities that provide finished cable assemblies; wiring harnesses, coaxial cable, high-temperature electrical wire, and control panel assemblies for the telecommunications, computer, and industrial control industries.

Our state of the art equipment and our well-trained staff provide consistently high-quality products to fill the most demanding requirements.

Contact us today at 905-624-5241 to learn more about our products and services.

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