An In-Depth Look into Fiber Optic Cables

The fiber optic cable has become a staple of long-range communications, as well as seeing use in various other industries. The way the cables work has allowed for greater distances without the need for more infrastructure to maintain signal strength. Their design has allowed them to become the new cable of choice for all manner of communications technologies.

However, most people don’t really know what a fiber optic cable is under the surface. What looks like a simple black cable is actually an impressive piece of modern technology. There’s some subtle engineering there, along with the fact that there’s more than one type. So now let’s take a good look at what a fiber optic cable is and what’s under the proverbial hood.

The Basic Structure

At the basic level, the typical fiber optic cable has a core, a steel wire to reinforce the filler, and a jacket that covers the whole. There are additional layers, as well. Waterproof sheaths, buffers, an insulated metallic wire, and a variety of other components. This combination makes them effective in conditions where older copper cores were not as effective.

The core functional element of the cable allows for the transmission of light as the signal. This is what grants fiber optics their speed and reliability, even over vast distances. The rest of the cable is just there to provide protection and support for the core.

The Core

Now, let’s take a good look at the core of the cable. This is the central portion, made out of silica glass. The strands are very thin and are the medium that allows for the transmission of optical signals. Fiber measurements in single mode cables are significantly thinner than the ones you’ll see in multi-mode cable designs.

The Cladding

Outside the core is the cladding, which is made of glass and immediately surrounds the central fiber. This assists in the transmission of the optical signal, as well as reflecting it back rather than letting it “leak” out. The result is improved signal strength and consistency. In general, the cladding is much thicker than the core itself.

The Primary Coating

Beyond the cladding is the primary coating, a buffer that protects what is within it. The main purpose is to add mechanical support, and the plastic used is extremely light and keeps it from adding anything to the overall weight. The point of this coating is to avoid external interference, keeping the light transmission in the innermost layers intact.

Kevlar Coating

The primary coating is itself often covered by kevlar. This layer of protection is meant to make the cable break-proof, allowing for easier installation. One of the risks without the kevlar coat is that it might break easily, especially if handled roughly. The kevlar takes the strain of being pulled through the duct, allowing the internal glass fiber and core to get through without being damaged.

The Outer Jacket

The outer jacket comes in various materials, with the decision made based on the site where the cable is deployed. This layer adds further mechanical support and protection, making sure everything inside remains intact and protected from the conditions of the environment.

Loose-Tube vs Tight-Buffered

There are two basic types of fiber optics. There are loose-tube cables and tight-buffered cables.

Loose-Tube Cables

Loose-tube cables have different colors, a form of coding that allows for easier identification. The plastic material buffer forms a protective layer for the optical fibers within. These also have a filler component of gel that allows it to be waterproof.

This type of cable has free movement, with a superior ability to contract and expand based on changes in external temperature. The bending ability also makes them better for areas with constricted spaces and difficult angles.

Tight-Buffered Cables

Tight-buffered cables have material to act as an additional buffer, with fiber closely attached to each other. The result is that the fiber is wrapped completely. This arrangement causes a ruggedness to the structure that makes it easier to handle and more likely to take no damage if handled without care. This makes installation easier and more seamless.

These cables use aramid yarn. This yard is placed outside the cale jacket or to cover each jacket individually. These layers provide further protection and are called sub-jackets.

Various Uses

These cables are used in various contexts and industries, of course. Most people would recognize them as being used in communications industries, specifically the internet and telephone lines. However, these cables have also seen use in other industries because of their flexibility and their use of light in transmitting data.

Military applications and industrial connections are among the most common. The aerospace industry also uses fiber optic technologies heavily. Fiber optic cables are also being used in the medical field, whether as part of procedures or for research purposes.


Fiber optics have helped improve many industries, whether by adding greater transmission speed or making them more consistent over long distances. The improvement has helped make things easier and more stable. These cables look simple, but a lot of work goes into making them and allowing them to function as effectively as they do.

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