What is an optical fiber and how is it constructed?

You are reading these words now thanks to the Internet. You probably came to this page thanks to a search engine like Google, which operates a worldwide network of giant data centers connected by high-capacity fiber-optic cables. What made it possible to accelerate data speeds in this way? Building a fiber-optic network that has been successfully displacing copper wires since the 1990s. More than 99% of data now flows through fiber optics. However, the high speed should be considered a novelty, as the Internet has only really developed since the 1990s. Today, we already have a 5G network that is more than 100,000 times faster than a few decades ago.

Fiber optics is a technology used to transmit information in the form of light pulses through glass or plastic fibers over long distances. Fiber optics are roughly the diameter of a strand of human hair, and when bundled into a fiber optic cable, they are able to transmit more data over longer distances and faster than other media. It is this technology that provides homes and businesses with fiber-optic Internet, telephone and television services.

What is fiber optics, how does it work, and why is it so superior to copper wires, which, after all, were used previously for more than 100 years?

What is a fiber optic cable?

Fiber optics is a technology that transmits information in the form of light pulses along a glass or plastic fiber. Fiber optic cable is a flexible, transparent conductor made of glass fiber and plastic. Fiber optic cable can contain a varying number of such glass fibers – from a few to several hundred. It is characterized by properties that allow light to be transmitted between its two ends, and even when the ends are placed hundreds of kilometers apart. Fiber optics transmit signals with less loss than conventional copper wires. Fiber optic cables are widely used because of their advantages over copper cables. Some of these benefits include higher bandwidth and transmission speed. They also show high resistance to electromagnetic interference, which is a major problem for metal cables. Thanks to its properties, optical fiber can transmit huge amounts of data, making it one of the pinnacles of the telecommunications industry.

Fiber optics is used in long-distance and high-performance data networks. It is also widely used in telecommunications services such as the Internet, television and telephones.

You’re certainly used to the idea of “information traveling” in various ways. When you’re talking about a landline phone, a wire cable carries the sound of your voice to a jack in the wall, where another cable carries it to the local telephone exchange. Cell phones work another way: they send and receive information using invisible radio waves – a technology called wireless because it doesn’t use wires. Fiber optics works in a third way. It sends information encoded in a beam of light. It was originally developed for endoscopes in the 1950s to help doctors look inside the human body without having to dissect it first. In the 1960s, engineers found a way to use the same technology to transmit phone calls at the speed of light.

Who invented fiber optics?

1840s: Swiss physicist Daniel Colladon (internal reflection of light in streams of water)
1930s: Heinrich Lamm and Walter Gerlach, two German students, tried to use fiber optics to make a gastroscope.
1950s: In England, physicist Narinder Kapany and physicist Harold Hopkins managed to transmit a simple image into an optical fiber made of thousands of glass fibers. After publishing many scientific papers, Kapany became known as the “father of fiber optics.”
1957: Three American scientists at the University of Michigan, successfully used fiber optic technology to create the world’s first gastroscope.
1960: physicist Charles Kao and George Hockham made a breakthrough discovery. Kao suggested that a fiber-optic cable made of pure glass would be able to carry telephone signals over much longer distances, and was awarded the 2009 Nobel Prize in Physics.
1960: Corning Glass Company scientists have created the first fiber-optic cable capable of carrying telephone signals.
~1970: Donald Keck and colleagues at Corning found ways to send signals much farther (with less loss), prompting the development of the first optical fibers.
1988: The first transatlantic fiber-optic telephone cable, TAT8, was laid between the United States, France and the United Kingdom.

Fiber optics began to be used on a large scale in the 1980s, allowing data transmission over a distance of 100 km. Steady development of the technology resulted in a range of up to 1,000 km with a speed of 10 GB/s.

Fiber optic vs. copper cables

Years ago, copper wire cables were one of the main choices in the telecommunications, networking and cable connection industries. Over time, however, fiber optics have become a common alternative. Most of the telephone companies’ long-distance lines are now made of fiber-optic cables.

Fiber optic cable carries more information than conventional copper wire, due to its higher bandwidth and higher speeds. Since glass does not conduct electricity, the optical fiber is not subject to various types of electromagnetic interference, and signal loss is minimized.

Advantages of fiber optics.

They support higher throughputs.
The light can travel farther without the need for signal amplification.
They are less susceptible to interference, such as electromagnetic interference.
They can be submerged in water.
Fiber optic cables are stronger, thinner and lighter than copper wire cables.
No maintenance or replacement is required.

What does fiber optics rely on?

A fiber optic network is compared to a road network for a reason. The fiber itself is small – about the same diameter as a strand of human hair – and the movement is in the form of light. Fiber optics transmit data in the form of light particles, or photons, which are transported through the fiber optic cable. The fiberglass core and sheath have different refractive indices that bend the incident light at a certain angle. When light signals are transmitted through an optical fiber cable, they bounce off the core and jacket in a series of zigzag reflections through a process called total internal reflection. The light signals do not travel at the speed of light due to the denser layers of glass; instead, they travel about 30% slower than the speed of light.

To the human eye, light appears white, but is actually composed of many colors. Fiber-optic cable is usually made of pure silica (glass) because of its properties to provide total internal refraction, the effect, forms the basis of fiber-optic communication.

Light travels down the core, which is protected by a coating that prevents light from escaping. Due to the properties of silica, light reflects inside the core instead of escaping, as if it were bouncing off a mirror. This can even be done uphill, producing light pulses that allow data transmission inside the fiber optic cable. The coating is used to protect it from damage and moisture.

Fiber optic cables can now support signals up to 10 Gbps. Typically, as the capacity of a fiber optic cable increases, it becomes more expensive.

How is a fiber optic cable constructed?

The most basic fiber optic cable consists of:

An internal element with a high refractive index, called the core;
The middle element with a lower refractive index, called the mantle;
An outer protective polymer layer (polyurethane or PVC) called a protective coating.

For glass optical fibers, the diameter of the core varies between 10-600 microns, the thickness of the sheath between 125-630 microns. For POF, all diameters are between 750-2000 microns. As you can see, one of the main differences between glass and plastic optical fibers is their diameter. This makes POF easier to handle.

The material used for currently available materials on the market includes pure glass, plastic or a combination of the two. The use of one or the other material will be determined by factors such as quality and economy.

Plastic optical fibers (POF) have the advantage of being made of cheaper materials than glass and operate in the visible spectrum. However, they exhibit high losses, so their applications are limited to transmission over short distances. Nonetheless, POF is widely used in medical and industrial tools, and research is currently underway to use POF as a replacement for copper wires for data transmission in automobiles.

Types of fiber optics

The types of fiber optics, or cables that take the form of bundles of many fibers connected together, are indeed many. The basic types are distinguished by the way the light beams are transmitted. Light signals in an optical fiber are carried in mods. A mod is the path that the light beam follows as it travels down the optical fiber. In this respect, fiber optics are divided into single-mode and multimode.

Single-mode optical fiber – the most common in the world’s telecommunications networks – is designed to transmit light energy along a single path over long distances. Its core is small – it is only 8 microns in diameter. It is most often used in long-distance networks. Since it supports only one light path, there is less likelihood of signal overlap and distortion. It is most often used in telephone and Internet networks, as well as cable TV.

On the other hand, multimode optical fiber has a larger core with a diameter of up to 62.5 microns. It is designed for light signals that must travel along many different paths simultaneously. They are used for interconnecting computer networks, among other things, because they can handle very large amounts of data in a space-efficient manner.

It’s also worth knowing that there are different ways to create fiber optic networks. The fastest networks are FTTH (Fibre to the Home) and FTTP (Fibre to the Premisses). Here the fiber is run directly to the recipient and gives the fastest speeds possible. All communication with the outside world is based on optical fibers. The FTTC, or fiber to the node, network relies on fiber being routed to a node in the vicinity of users, who in turn connect to such a node using traditional copper cables.

Fiber optics not only in telecommunications

Telecommunications is, of course, the primary use of fiber optics. More than 99% of the world’s data already travels via fiber optics. But that’s not all.

Just two years after the first modern fiber optics were patented, they landed on the moon (a basic component of the television cameras used by NASA). Their use was even kept secret. To date, fiber optics are also used in the military (locating enemy ships as part of sonar systems). Fiber optics are also relied upon for seismographs. Sometimes, however, they also have mundane applications – for example, for light installations. For more information on applications, see below.

Applications of fiber optics

Computer networks

Computer networks – for their ability to transmit data and provide high bandwidth. Similarly, fiber optics are often used in electronics to provide better connectivity and performance.

Internet and cable TV

Internet and cable TV are two of the most common uses of fiber optics. Fiber optics can be installed to support long-distance connections between computer networks in different locations.

Marine areas

Fiber optic cables are used in more unusual environments, such as undersea cables, because they can be submerged in water and do not require frequent replacement.

Military and space

The military and space industries also use fiber optics as a means of communication and signal transmission, in addition to its ability to detect temperature. Fiber optic cables can be advantageous due to their lighter weight and size.

Medical

Fiber optics are often used in various medical tools to provide precise illumination. Biomedical sensors are also increasingly becoming available to aid in minimally invasive medical procedures. Because fiber optics are not subject to electromagnetic interference, they are ideal for various tests, such as MRI scans. Other medical applications for fiber optics include X-ray imaging, endoscopy, light therapy and surgical microscopy.

Is there fiber optic at your place? Get to know ITH Net!

There has been rapid development of the fiber optic network, making the price of an Internet connection much lower than it used to be. The map of the fiber-optic network is getting denser and the availability of fiber-optic cable is also increasing. Both individual users and companies can benefit from it. ITH Net provides Internet connection services for businesses. It offers symmetrical lines for business implemented over a fiber-optic network. The services are all the more advantageous because the company has them as an anti-crisis offer. Until December 31, 2022, you can use the full offer for only 1 zloty. After that, you can decide whether to terminate or continue your cooperation with the company. There is one condition – the ITH anti-crisis shield must be available at your company’s location. Within 7 days of signing the contract, the installation of the ITH Net service takes place. There are several attractive service packages to choose from. The ITH infrastructure is based on a fiber-optic network and distributed access nodes. For Krakow and Warsaw, they have two telecommunications nodes each, independent of each other. In the network, the company uses equipment from manufacturers such as Huawei and Juniper.

What is an optical fiber and how is it constructed?