Investigation of Raman fiber amplifier with all optical gain clamping

Summary form only given. We experimentally investigated the issue of dynamic gain clamping for a fiber Raman amplifier. The basic idea is introducing an all-optical feedback lasing signal sustained by the amplifier itself, similar to a gain-clamped EDFA. From its ASE spectrum, the gain variations due to signal cross saturation can be suppressed to a great extent by introducing all-optical feedbacks, the gain variation can be locked to less than 1 dB. A better gain-clamping is achieved when clamping wavelength is in a relatively low gain regime. Our experimental results also shown signal gain fluctuation are serious at up-shift wavelength rather than down-shifted wavelength from the clamping wavelength.