Context:
Article in The Hindu – Fibre optic cables: its origins, working and different functions.
Fibre Optic Cables
What are they?
- Made of thin cylindrical strands of glass.
- Carries information, such as text, images, videos, telephone calls, and anything that can be encoded as digital information, across large distances almost at the speed of light.
- Features – Strong, light, and flexible, easily buried underground, drawn underwater, or bent around a spool.
- Applications – telecommunication, medical science, laser technology, and sensing.
Working:
- Air to Glass –
- 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.
- Glass to Air –
- When a beam travels from glass to air, it won’t enter the air and instead, it will be completely reflected back within the glass. This is known as total internal reflection.
- Thus 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.
The refractive index is the property of a medium that determines how fast light can travel in it.
Components of fibre optic communication system:
- Transmitter which encodes information into optical signals
- An optical fibre that carries the signal to its destination
- A receiver which reproduces the information from the encoded signal
Total Internal Reflection is the basis of guiding light across long distances without a significant loss of optical power.
Today’s optical fibres have a typical loss of less than 0.2 dB/km.
Source: The Hindu
Previous Year Question
With reference to Visible Light Communication (VLC) technology, which of the following statements are correct?
1. VLC uses electromagnetic spectrum wavelengths 375 to 780 nm.
2. VLC is known as long-range optical wireless communication.
3. VLC can transmit large amounts of data faster than Bluetooth.
4. VLC has no electromagnetic interference.
Select the correct answer using the code given below:
[UPSC Civil Services Exam – 2020 Prelims]
(a) 1, 2 and 3 only
(b) 1, 2 and 4 only
(c) 1, 3 and 4 only
(d) 2, 3 and 4 only
Answer: (c)
