A novel compensating light injection configuration for gain-clamped EDFA's

A novel compensating light injection configuration for gain-clamped erbium-doped fiber amplifier (EDFA's) is proposed. The compensating light is backward injected from the end of the first stage of the amplifier and then reflected by a grating at the amplifier input end. Very wide input dynamic range (0.5 μW-500 μW) with less than 1 mW of compensating light and low noise penalty (<0.5 dB) is demonstrated.