Multistage Optical Amplifier Gain Compensation

The patent applies preliminary action by adjusting the pumping power of subsequent amplifier stages before the power change actually occurs at their input. The control device calculates and sets the new pumping power based on expected changes detected at the first stage, anticipating the power variation and compensating for it in advance. This prevents overshooting and undershooting by acting before the disturbance reaches the system, thereby maintaining both stability and precision.

The patent applies preliminary anti-action by implementing a control mechanism that anticipates power changes and applies counteracting adjustments to the pumping power before the changes propagate through the amplifier stages. The control device detects power changes at the first stage and preemptively adjusts subsequent stages' pumping power in the opposite direction of the expected gain variation. This counter-action, applied in advance, cancels out the harmful gain variations while maintaining fast response, resolving the contradiction between speed and constancy.

The patent applies feedback by implementing a control device that continuously monitors the input power at the first amplifier stage and uses this information to adjust the pumping power of subsequent stages. This feedback mechanism creates a closed-loop control system where gain variations in early stages are detected and compensated for in later stages. The feedback approach enables multistage amplification to maintain constant overall gain, preventing cumulative variations that would otherwise cause bit errors, thus preserving transmission reliability while maintaining high amplification capability.