Fibre optic material dispersion
The different wavelengths of light and other electromagnetic waves have speeds that vary very slightly.
Red light, for example, travels slightly faster than blue light.
While usually this wouldn’t be an issue, in fibre-optic cables, light is often sent over long distances. We don’t want different components of the light arriving at different times!
This is often called pulse broadening.
Why not send white light?
White light is made up of all the colours. If we sent white light down a fibre-optic cable, then we actually send multiple differnent wavelengths which will arrive at different times.
Solution
We can solve this problem by sending monochromatic light (only one wavelength) instead of white light.
flashcards
| Question | Answer |
|---|---|
| What is the phenomenon called when different wavelengths travel at different speeds, causing signal spreading in fibre optics? | Pulse broadening (or material dispersion). |
| Why does sending white light cause pulse broadening in fibre optics? | White light contains many wavelengths, which travel at different speeds and arrive at different times. |
| How can you prevent material dispersion in fibre optics? | By sending monochromatic light (single wavelength) instead of white light. |