Why Receiver Sensitivity is so important for optical module?

Why Receiver Sensitivity is so important for optical module?

For Optical communication to happen, a receiver (essentially a photodetector, either a PIN or APD type) needs a minimum amount of power to distinguish the 0s and 1s from the raw input optical signal.

The minimum power requirement of the receiver is called the receiver sensitivity

The optical power at the receiver end has to be within the dynamic range of the receiver;
otherwise, it damages the receiver (if it exceeds the maximum value) or the receiver cannot
differentiate between 1s and 0s if the power level is less than the minimum value.