What is Optical Fiber and a Fiber Optic Cable?


Fiber Optics –
A faster way to communicate.

Optical fiber nomenclature comprises two words, optical which refers to light, and fiber which refers to a material of glass or plastic.

It is a new-age technology leveraging the information or data transmission over a special wire-like object. Which is highly advanced as compared to copper wires since it transmits signals from one destination to the other which may even be a thousand miles apart.

What is Fiber Optic Cable?

A communication wire manufactured based on fiber optics technology is known as fiber optics cable. These are highly efficient cables that are many-fold powerful than ordinary copper cables in terms of data transfer speeds.

fiber optic cable diagram
fiber optic cable diagram

Their innate property is not just transmitting highly efficient signals, but also preventing any losses that occur due to unfavorable conditions like bending, cracks, and even electromagnetic interference due to weather disturbances.

The optical fiber cable looks like a tube as shown in the image above. It must be noted that light rays travel through the core. The core is surrounded by cladding and packed in a plastic coating.

It must be ensured that the protection of these optical fibers, which is done through the outer cladding, must be of high standards since it gives overall protection to the cables.

Their working principle is TIR (total internal reflection) which is explained further.

What is Optical Technology?

An optical fiber cable comprises hair-like thin strands made up of either glass or even plastic. It is pertinent to note that human hair is 10 times thicker than the strand.

But at the same time has the capacity to carry more than 20,000 calls which when collectively considered as an optical fiber has this capacity to carry million telephonic calls.

As the entire information carriage relies upon a technology that is based on the light. The capacity can be estimated from an established benchmark that has been set for 178 terabits (1 terabit = 1 trillion bits) per second which can be compared as having around half a billion online video sessions over Microsoft teams or Google meet platform.

How does a fiber optical cable work?

As explained above, fiber optics have been assigned a key role of transmitting data from one destination to the other essentially as light particles.

They can also be termed photons that travel through this optical fiber. Bringing to the point mentioned earlier, which is the principle of TIR or total internal reflection.

How fiber optics works

These light waves travel through the optical fiber cable, say in a zig-zag manner, experiencing reflection through their journey of traveling through the core and cladding. 

Technically mentioned here, the refractive index of the cladding should be lesser than the core.  The angle at which light gets reflected from the glass should be less than 42 degrees, in order to ensure that reflection occurs again and works like a mirror.

This modus operandi is called TIR  or Total Internal Reflection. 

Is data speed the same as the speed of Light?

One may always be apprehensive about their velocity and could believe that it could be comparable to the speed of light, but it is pertinent to note that the speed is about 1/3 (one-third) in this medium as compared to the speed of light, because the density of the glass medium is higher, leading to the reduction in the speed.

 How to prevent losses for a long-distances? 

Although a fiber optic cable covers a much longer distance than a legacy wired cable. But at times, when the distances of this journey increase beyond a certain range, a special kind of device called a repeater is introduced.

The core objective behind introducing these repeaters is to ensure that the signals reaching the destination carry all the meaningful information and must not have any signal loss.  These days, fiber optics provide signal strength up to 10Gbps but having said that it comes at an additional cost. 

Overview of a Fiber Optic Network.

A fiber-optic network curated out of these optical fibers facilitates the end-to-end process of communicating the signals.

The first one and the fastest one is popularly known as FTTH (fiber to the home) or FTTP (fiber to the premises). It is named in this way because optical fibers, when installed with the terminals, connect the houses, offices, or large buildings.

FTTC (fiber to the curb) on the parallel front, is a semi or partial fiber connection. Since the fiber optics reach the curb or the hub located near the homes and businesses while further.

Copper cables are given the responsibility of signals to travel from the curb to the rest of the way.

Classification of Fiber Optics.

The classification is based on various parameters. Following are the types.

Technical Classification-

Fiber optics classification based on distance.

The first classification is based on distance. It is interesting to note that for shorter distances, multimode fiber is used wherein every single optical fiber used is 10 folds larger than that in the single-mode fiber. Its application is linking computer networks.

Whereas long-distance transmission is carried over single-mode fiber, it comprises a thin core that has a diameter of the tune of a millionth of a meter or specifically, in this range of 5-10 microns. An application of this category is telephone communication, internet, or even cable TV network.

Fiber optics classification based on refractive index.

Second, depending upon the refractive index of the optical fiber, the classification is of further two types. The first one is called a step-index fiber, which consists of a core surrounded by a cladding and must possess a single uniform index pertaining to the refraction.

The second classification in this category is called graded-index fiber where it is learned that the refractive index of the fiber diminishes with respect to the increase in radial distance from the fiber axis.

Fiber optics classification based on the material used.

The third classification of optical fiber can be done on the basis of the material used. The two categories are plastic optical fibers and glass fibers.

Plastic optical fiber uses polymethylmethacrylate material for light transmission while glass fiber uses superfine glass material.

What is the commercial classification of Fiber optics?

Using the above classifications we can come to the conclusion of four combinations of optical fibers-

  • the first one being step-index single-mode fibers
  • the second can be termed as graded-index single-mode fibers
  • the 3rd categorized as step-index multimode fibers
  • the 4th one is graded-index multimode fibers

What are the Advantages and Disadvantages of Fiber Optics?

What are the Advantages of fiber optics?

The key properties of fiber optics mentioned here together form the biggest advantage of fiber optic cables is long-distance data travel with less or almost negligible loss of signals.

Their advantages are : 

High Bandwidth: Capacity to carry many folds larger information as compared to ve traditional copper cables

Interference Resistance: The resistance to electromagnetic interference, which ensures no disturbances, is a superlative property making optical fibers an extremely reliable source of transmitting information

Minimal Attenuation: This indicates less signal loss, which also stays intact which very less use of amplifiers, which otherwise are needed after a certain distance, again 10 folds longer than the copper wires.

What are the Disadvantages of fiber optics?

The first point accounting for the disadvantage is the cost element which is very higher than that of the copper wires. Their CAPEX (capital expenditure) also includes installation which makes the one-time cost increase furthermore. As they have glass material, bends or curves near to the radius should also be treated with utmost care.

Uses and spread of Fiber Optics?

What are the Uses of fiber optics?

Now that we have discussed their properties, advantages as well the disadvantages, uses of fiber optics must be learned. It is not an exaggeration of the fact that they form the backbone of the network around us.

Be it telecommunication, internet, or computer networking, optical fibers form an integral part of these operations.

Reiterating the fact that optical fiber cables hold an inseparable role in the Computer Networks, by virtue of certain unparalleled innate advantages of fiber-optic cables.

Fiber optics usage in broadcasting 

Broadcasting has also seen a paradigm shift from an era of rooftops full of antennas to an age of fiber-optic cables reaching directly to our homes and thus, providing better videos and audio quality.

The copper cables covered in metal protection (coaxial cables) deployed in the earlier times of the 1950s onwards had challenges including those of interferences, largely responsible for a poor entertainment experience.

Now is the time when we come across experiences of Internal Protocol Television or IPTV, and unmatched experiences of OTT platforms. 

Fiber optics usage other than basic network connectivity and broadcasting.

The application of fiber optics also has a significant contribution in the medical fraternity that includes various tests like X-ray imaging, MRI scans, endoscopy, etc.

Military operations and space initiatives also utilize the power optical fibers for transferring signals and sensing the temperature.

Spread of fiber optics 

The growth rate of laying down optical fibers has shown a steep growth. As per the reports of TeleGeography of the year 2020, presently there are 406 optical fiber submarine cables, covering a total distance of 0.7 million miles or 1.2 million kilometers.

This is an increase over the 2019 report of 378 optical fiber cables that were laid. 

Discussion Summary:

All these above-mentioned uses, given the innate properties of optical fiber, help us conclude with the supporting facts that optical fiber or fiber optics have a sacrosanct unparalleled contribution in the telecommunication and networking space.

The properties of the fiber and efficiency of signal to travel inside the special glass materials make them irreplaceable in today’s time. Thanks to these fiber optics, that is helping us transmit this information through our blog to you.