Output-residual-driven adaptive narrowband feedforward method for suppressing power jitter in EDFA systems

This paper proposes an output-residual-driven adaptive narrowband feedforward method for suppressing optical power jitter in EDFA systems. The proposed scheme uses a pump-based feedback loop for slow operating-point recovery and a VOA-based feedforward branch for targeted narrowband compensation. To avoid forcing the pump loop to track non-service-level jitter, an event-triggered baseline estimation mechanism is introduced to generate a slowly varying output reference. Meanwhile, power-domain I/Q demodulation is performed on the output error signal to extract the residual component at the locked disturbance frequency, and a secondary-path-aware I/Q-LMS update is used to adaptively correct the VOA compensation coefficients online. Numerical simulations based on a dynamic EDFA model show that the proposed method significantly reduces output ripple and suppresses the target-frequency residual while maintaining the desired gain after add/drop-induced operating-point transitions. Additional simulations under frequency variation, secondary-path mismatch, sparse multi-frequency disturbances, and a six-stage cascaded amplification further support the robustness and applicability of the proposed local control strategy.