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Fibre optic cables

  • Published
    28th Nov, 2023

Along with quantum optics, fibre optic communication stands on the cusp of a new era.


During the COVID-19 pandemic, the one thing that connected us virtually was the internet, it helped in video chat with a friend, pay online, and attend classes or meetings from home.

What is an optical fibre?

  • Optical fibres are made of thin cylindrical strands of glass.
  • The diameter of a typical fibre is close to the diameter of a human hair.
  • These fibres can carry information, such as text, images, voices, videos, telephone calls, and anything that can be encoded as digital information, across large distances almost at the speed of light.
  • Receiving text messages and phone calls is a part of our everyday life, and most of us may have taken it for granted. But optical fibres are an essential part of this development in communication.
  • Ultra-thin fibres seem very fragile. But when manufactured correctly as a long thread surrounded by protectives, they serve the purpose in a durable way.
  • They are strong, light, and flexible, and ideal to be buried underground, drawn underwater, or bent around a spool.

How do optical fibres work?

  • Electromagnetic wave: Light is an electromagnetic wave with a spectrum of frequencies. Visible light, X-rays, radio waves, and thermal radiation (heat) all lie on this spectrum. Humans see the world around us via sunlight, but it took us a long time to control and guide light through fibre optic cables – or “light pipes” – to send coded signals.
  • Reflection:When a beam of light falls on a glass surface, it passes through partially while the rest is reflected away. When it passes through, its path bends because the refractive index of glass is different from that of air. The refractive index is the property of a medium that determines how fast light can travel in it.
  • Total internal reflection: When a beam travels in the reverse direction, i.e. from glass to air, it’s possible that it won’t enter the air. Instead, it will be completely reflected back within the glass. This phenomenon, known as total internal reflection, is the basis of guiding light across long distances without a significant loss of optical power.
  • Encoding of signal:This is how signals encoded as electromagnetic waves can be fed into one end of an optical fibre, and they will reflect and bounce many times between the glass walls as they traverse several kilometres bearing the information in the signals.
  • Components of communication system:A fibre optic communication system consists of three parts.
    • A transmitter encodes information into optical signals (in the form of rapidly blinking light pulses of zeros and ones).
    • An optical fibre carries the signal to its destination.
    • There, a receiver reproduces the information from the encoded signal.
  • Weather Proof:Optical waves allow a high data-transmission rate, up to several terabits per second in a single fibre. Unlike radio or copper-cable-based communication, fibre cables are also insensitive to external perturbations such as lightning and bad weather.

Way Forward: Future of fibre optic cables

  • Fibre optics technology has since been widely used in telecommunication, medical science, laser technology, and sensing.
  • With a goal to securing communication and promoting quantum science, the Government of India announced a national mission in the Union Budget of 2020. The proposed budget for this ‘National Mission on Quantum Technologies and Applications’ is Rs 8,000 crore over a period of five years.
  • The possibilities of fibre optic networks are growing at an accelerated rate, reaching all the way into our homes. Along with quantum optics, fibre optic communication stands on the cusp of a new era.
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