What happens if you feed a optical node with a too high level of light?

If the received light level is too high for the detector in an active node, the result of overdriving the detector can cause noise in the signal, or worse case even damage to the unit.

The answer is an attenuator.

Attenuators are available in either fixed or variable levels of attenuation, and as pigtailed devices, bulkhead adapters, or male-to-female hybrids. Simply measure the power of the signal being received, and subtract the maximum input power of the active equipment from the measured power of the signal to determine the amount of attenuation needed.