A receiver node includes an optical amplifier optically coupled to the
input of a receiving device such as a PIN photodiode. A controller inputs
received power level values from the receiver to perform gain control. The
input signal of an optical receiving device is pre-amplified by an optical
amplifier such that the amplified signal is within a dynamic range of the
receiving device. Windows are utilized to trigger the gain control
algorithm such that when the received power level is inside a first window
the gain control is turned off. When the received power level is outside
the second window, the gain control is turned on. Additional windows may
be used to adjust the rate of gain change. The rate of gain change is
decreased as the magnitude of the difference between the current received
power level and the target received power level decreases. Pump power
levels may be fed back to the controller such that a soft limit may be
imposed on to limit he maximum pump power and thereby prevent receiver
damage.