An automatic-gain-controlled Raman fiber amplifier/gain-clamped SOA for metro WDM networks with changes in span loss

We propose an automatic-gain-controlled Raman fiber amplifier/gain-clamped semiconductor optical amplifier. The amplifier uses a feedforward gain-control scheme to maintain the channel output power. The signal power after the optical amplifier is automatically controlled to within 0.15 dB when the span loss changes from 16 to 26 dB.