Raman amplification of recirculating pulses in a reentrant fiber loop

Abstract

We report the generation of a train of 130 optical pulses derived from a single input pulse recirculating in an active reentrant fiber loop. This was achieved in a 810-m-long single-mode fiber loop closed by a fiber directional coupler. Propagation loss and coupler bifurcation of the 1.12-microm signal were compensated for by Raman amplification using 1.064-microm pump pulses. The effects of pump-power fluctuations on the pulse's amplitude stability and background noise are also reported.