Advantages & Disadvantages of optical fibre over normal electrical cables

Key idea: H3 Photonics: Advantages & Disadvantages of optical fibre over normal electrical cables — key ideas and exam-focused notes on reflection, refraction, polarisation, fibres, and attenuation.

  • Advanced Physics
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Learning objectives

  • Use advanced reference material to reinforce mathematical, optical, material, and modern-physics models.

Advantages:

  • Information can be carried by radio waves transmitted down coaxial cables at a rate of about 107 bits per second. But this can be increased by several orders of magnitude if information is carried as light pulses down an optical fibre. A typical optical fibre cable can carry about 9000 telephone channels, or over 1000 music channels, or 8 television channels, which is over five times the capacity of the best copper cable.
  • Optical fibres can carry information over greater distances without significant attenuation. Coppoer cables require boosters to be spaced much closer together.
  • An optical fibre cable is lighter, smaller and easier to handle than a copper cable.
  • Optical signals are free from ‘noise’ due to electrical interference.
  • ‘Crosstalk’ between adjacent channels is negligible.
  • Also, because light waves do not create an external magnetic field (unlike an electric current flowing down a wire), they are far less susceptible to external surveillance.
  • Apart from communication, optical fibres can be used as endoscopes in medicine and engineering to ‘see’ inaccessible places. This means that ‘exploratory surgery’ can be avoided.

Disadvantages:

  • Limited physical arc of cable. Bend it too much and it will break.

  • Difficult to splice.

  • Physical vibration will show up as signal noise.

  • Loss of light in fibre due to scattering. (Attenuation)

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Course and syllabus information
Course
Advanced Physics
Edition
Advanced Physics