Optical Fibre Cable: Working, Applications & More

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We discuss the following topics in this blog:

  1. The science behind fibre optic cables
  2. What is an Optical fibre cable (OFC)?
  3. Optical fibre cable (OFC) manufacturing in India
  4. What are the different types of fibre optic cable
  5. Difference between multimode and single-mode fibre optic cable
  6. What is fibre optic cable used for?

In addition to these topics, we shall also be answering the following FAQs:

  1. Who invented fiber optics?
  2. What are the 2 types of fiber optic cable?
  3. What equipment is needed for fiber optic Internet?
  4. What is used for the fabrication of optical fibers that are used for communication?
  5. Why silica is used for the fabrication of optical fibers?
  6. What is the principle of fiber optical communication?
  7. What is the bandwidth of optical fiber?
  8. List a few advantages of optical fiber communication?


The need to stay always connected, for individuals as well as for enterprises, has set the demand rolling for high internet speeds with high quality and consistency. Further, innovations in the telecom sector have increased the deployment of broadband-based network architectures. This all has given a huge growth opportunity for the fiber optic cable industry.

The Science Behind Fibre Optic Cables

Fiber is hair-thin material made of glass. Generally, optical fiber has a diameter of 125 micrometres (μm), which is actually the diameter of the cladding, or outer reflecting layer. The core, or inner transmitting cylinder, may have a much smaller diameter (sometimes 10 μm). Light rays beam into the fibre within the core through the process of total internal reflection. This can happen for great distances with little attenuation or reduction in density. The degree of attenuation varies according to the wavelength with little attenuation in intensity.

What is OFC (Optical Fibre Cable)?

A fiber-optic cable is composed of very thin strands of glass or plastic known as optical fibers; one cable can have as few as two strands or as many as several hundreds of them. These optical fiber cables carry information in the form of data between two places using optical or light-based technology. Once the light beams travel down the optical fiber cable (OFC), they would emerge at the other end. A photoelectric cell will be required to turn the pulses of light back into electrical information the computer could understand.

While travelling down fiber optic cable, light repeatedly off the walls. The beam of light does not leak out of the edges because it hits the glass at really shallow angles. And then it reflects back again as if the glass was really a mirror. This is called total internal reflection. The other factor that keeps it in the pipe is the cable structure.

Fiber offers many advantages, the prime ones being higher bandwidth and reach. Optical fibre cables (OFC) are now preferred over old copper telecom cables as they provide high-speed broadband services. Optical fibre loses 3% of the signal over 100 meters distance while copper wires lose 94%. Additionally, optical fibres are more long-lasting as compared to copper wires, which are much fragile. Copper wire can be tapped very easily, while optical fibres do not radiate signals that can be tapped. Optical fibre offers much lower latency (the amount of time required to perform data transmission) compared to copper wires.

Let’s hear it from the Horse’s mouth more on Optical Fibre Cables (OFCs)

Optical Fibre Cable Manufacturing in India

The Indian optical fiber cable market is gaining traction. The growth is driven by continued investments being made by the Indian government in developing OFC network infrastructure, in various projects. The Indian market for optical fibre cable (OFC) is projected to grow at a CAGR of 17% through 2023. There has been increased adoption of Fiber-to-the-Home (FTTH) connectivity owing to government initiatives such as Digital India, Smart Cities, or Bharatnet. Moreover, the growing number of data centres in India will fuel this growth further.

The Telecom industry is the primary user of optical fiber technology. The increasing need for 24X7 high-speed connectivity and an increase in data traffic due to services such as voice, messaging emails, downloads, and video streaming.

Indian OFC manufacturers have been making great efforts to meet domestic demand for optic fibre cable. For this, they also need support to ensure sustainable development to the overall economy. In several developed countries, initiatives like tax incentives, substantial project subsidies, financial support for R&D have assisted domestic players to proliferate. The Indian manufacturers have the capability and capacity and they also need a similar kind of support from the government.

STL Tech is one of the most trusted end-to-end fibre optic cable manufacturers and the only company in the world with a fully integrated silicon-to-software pipeline. We specialise in everything from manufacturing optical fiber cables of various types and for various applications, to designing and installing integrated hyper-scale fibre optic networks. STL’s innovative optical fibre products are utilised in a plethora of large-scale applications such as long-haul, metropolitan, FTTx, CATV, smart city, intelligent traffic networks, access, defence-security, and premise. We also specialise in various optical fiber cable configurations such as ribbon, loose tube and tight buffered for all types of aerial and underground deployments.

Since 2019, STL has invested over INR 1500 crores in expanding its optical fibre manufacturing capacity from 30,000 fibre km to 50,000 fibre km. Our global optical fiber network currently stands at 33 million fibre km, catering to India and other international geographies like the UK and the US. STL’s worldwide footprint encapsualtes next-gen optical preform, fibre, cable, and interconnect subsystem manufacturing facilities in countries like India, China, Brazil, and Italy.

STL partners with telecom operators, government organisations, internet service providers, infrastructure companies, public utility providers, and more in order to deliver and install high-end, high-performance optical fibre networks of the future. In India, STL has partnered with various state governments to maintain the country’s nationwide optic fiber network program – BharatNet. Moreover, STL’s Centre of Excellence offers state-of-the-art core research and development in fibre technology and has yielded over 216 patents in the industry.

What are the Different Types of Fibre Optic Cables?

The optical fibre cable is classified based on 3 factors – the refractive index, materials used, and mode of propagation of light.

The basis on refractive index OFC is of two types:

  • Step Index Fibers: It comprises a core enclosed by the cladding, which has a single uniform index of refraction.
  • Graded Index Fibers: The refractive index of the optical fiber decreases as the radial distance from the fiber axis increases.

Based on materials, OFC is of 2 types:

  • Plastic Optical Fibers: The poly(methyl methacrylate) is used as a core material for the transmission of light.
  • Glass Fibers: It consists of extremely fine glass fibers.

Based on the mode of propagation of light, OFC is divided into:

  • Single-Mode Fibers: Used for long-distance transmission of signals.
  • Multimode Fibers: Used for short-distance transmission of signals.

Difference Between Multimode and Singlemode Fibre Optic Cable

Based on product type, the market can be divided into singlemode fiber and multi-mode fiber. Single mode fiber allows one type of light mode to be propagated at a time. However, multi-mode fiber cable can propagate multiple modes. Multi-mode optical fiber can be used for short-distance runs, while single mode fiber cable can be used for long-distance applications. Hence, single mode fiber segment is expected to grow much faster during the forecast period owing to their long-distance applications and low installation cost as compared to multi-mode fiber.

Single mode fiber’s core diameter (9 µm) is much smaller than multimode fiber (50 µm and 62.5 µm). Its typical core diameter is 9 µm. This enables the multimode fiber to have a higher “light-gathering” ability and simplify connections. The cladding diameter of single mode and multimode fiber is 125 µm.

What is Optic Fibre Cable Used for?

Fiber optic cables can carry enormous volumes of data at very high speeds. For this reason, fiber optic technology serves various purposes.

High-speed Internet

Fiber optic cables are less bulky, lighter, more flexible, and carry more data as compared to copper cables


Whether it is between computers within a building or across the buildings, fiber optic cable is always a preferred mode for faster networking.

Data centres

It is used for connecting edge data centers or for structured cabling within the data centres as well.

Defence application

Very high level of data security is required within military and aerospace applications. Fibre optic cables offer the ideal solution for data transmission in the defence sector.


Who Invented Fibre Optics?

Charles Kuen Kao discovered certain physical properties of glass in 1960s, which laid the groundwork for high-speed data communication in the Information Age

What are the 2 Types of Fibre Optic Cable?

There are two types of fibre optic cables – multimode and single-mode. Multimode fibre is capable of carrying multiple light rays (modes) at the same time as it has varying optical properties at the core. Single-mode fibre has a much smaller core size (9 microns). It has a single light path and can travel much longer distances of up to 100km. 

What Equipment is Needed for Fibre Optic Internet?

Service providers require a fiber-ready router (often called a “residential gateway” by internet providers) in order to accommodate fiber-optic speeds

What is Used for the Fabrication of Optical Fibres That are Used for Communication?

Optical fibers are fabricated in a multi-step process:
First, there is a preform fabrication, followed by fibre drawing, fibre coating, and spooling. A preform is a giant-sized version of the final fiber product. It has a central core and cladding refractive indices that are equal to those of the desired product.

Why Silica is Used for the Fabrication of the Optical Fibers?

Because silica has a wide wavelength range with good optical transparency. It can be drawn into fibres at reasonably high temperatures and has a conveniently broad glass transition (a relatively shallow viscosity curve).

What is the Principle of Fibre Optical Communication?

Fiber optical communication works on the principle of total internal reflection by which light signals can be transmitted from one location to another with zero loss of energy.

What is the Bandwidth of Optical Fiber?

Optical fibre has high bandwidth due to the speed at which data can be transmitted and the range of frequencies over which data can travel without any attenuation.

List a Few Advantages of Optical Fiber Communication.

  1. Fiber optic cable has a much higher bandwidth as compared to copper cables.
  2. It can transfer much amount of data as compared to other metal cables.
  3. Economical & cost-efficient with less power consumption.
  4. Durable & flexible with less signal degradation.

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