- Study Helper
Why infra-red radiation rather than visible light usually used in optic fibres?
It's because infra red has a longer wavelength than visible light and is not attenuated (scattered and absorbed) as much by the glass fibres at these wavelengths, thus preserving the signal to noise ratio over longer distances.
The transmitted signal can therefore travel much further without needing a repeater station (amplifier) to both clean up and boost the signal at regularly spaced intervals. This reduces the cost of long distance installations, operation and maintenance considerably.