Page 27 - Flipped book_fiber optics

ii. Chromatic Dispersion / Intramodal Dispersion

Is caused by the fact that fibers transmit light of different
wavelengths through different materials at different speeds.

Occurs in both single mode and multimode fiber
Larger effect with LEDs than with lasers

A far smaller effect than modal dispersion

Modal Dispersion / Intermodal Dispersion

 Spreading of a pulse because different modes (paths)
through the fibre take different times, i.e. light rays

travelling in each mode will travel a different distance
they will arrive at the output at different times.

 Only happens in multimode fiber ; limits its performance
 As length fibre increase, modal dispersion increase

 Will be reduced with graded-index fibre.