Optical gain stabilization of a distributed fiber Raman amplifier

he system of optical stabilization (Gain Clamping, GC) for gain of distributed SRS optical amplifier with forward pumping (Forward Distributed Raman Amplifier Unit, F-DRAU) was experimentally studied. For optical stabilization, spectrally selective, within one channel, optical feedback is created in the form of a linear resonator with Faraday mirrors. When the gain is unsaturated and exceeds the losses in the feedback circuit, generation occurs, ensuring stabilization of the gain at a level that exactly compensates the losses in the feedback circuit. The effect on the gain of individual channels of changes in the RAU pump power and the input power to the line was studied. It has been shown that optical stabilization makes it possible to reduce gain variations when changing the pump laser power and the total input power of the multichannel signal. In particular, it is shown that when using the proposed feedback method, changes in gain caused by fluctuations in input power by 8 dB were reduced from 1.9 dB to 0.2 dB. An algorithm for auto-tuning the pump power is proposed. This algorithm makes it possible to reduce the skew of the gain spectrum in a Raman amplifier with feedback and reduce energy consumption.