1) According to theoretical characteristic of a LED and using direct modulation, if an input
signal is a sine wave, what would the output signal be?
2) If receiving optical powers for the red and green channel are 200 micro-watt, and a same
photodiode is used for both channels, calculate currents received by both channels.
1. LED works as current rectifier which passes current only in one direction. Thus, the output signal is a sine wave without negative halfwave.