Design and analysis of dynamic erbium-doped fiber amplifier gain-clamping systems with feedback control

We present an accurate and quantitative design scheme for erbium-doped fiber amplifier (EDFA) gain control systems. The proposed design scheme is demonstrated through the design of an eight-channel EDFA gain-clamping system with an all-optical self-tuning feedback loop. The effect of the time delay in the feedback loop and the selection of feedback wavelength are theoretically analyzed. Compared with existing electrical-optical EDFA gain schemes, the proposed design scheme is free from the feedback loop response speed limitation and does not need any predetermined information of the network traffic variation or operation point estimation. It can efficiently enhance the static and dynamic performance of the whole system. Furthermore, since the design can efficiently suppress the relaxation oscillation transient, it provides a cost-effective solution for the gain-clamping problem of a long EDFA chain by combining it with a fast-link control method. (c) 2007 Optical Society of America.