All optical gain-clamping in erbium-doped fiber amplifier using stimulated Brillouin scattering

A novel structure of gain clamping in an erbium doped fiber amplifier (EDFA) is demonstrated. Stimulated Brillouin scattering (SBS) from a dispersion compensating fiber module is used as feedback to clamp the gain of the conventional two-stage EDFA. A counter propagating continuous-wave probe beam at 1559 nm operating effectively at -9.5 dBm is used as the SBS pump source. For a dynamic range of 10 dB per channel, gain variation is kept below 1 dB for a single surviving channel in an eight-channel wavelength-division multiplexer.