Parametric interactions between pumps and signals in a co-pumped Raman amplifier

Summary form only given. Distributed Raman amplification can increase transmission distance and is essential for high bit-rate (10 Gb/s and higher) systems. Counter-pumped Raman amplification is preferable because the relative intensity noise (RIN) transferred from pump to signal is less than that of co-pumped Raman amplification. However, recent studies show that combining co-pumped Raman amplification with counter-pumped Raman amplification helps to increase optical signal-to-noise ratio (OSNR). In this paper, we report the parametric interactions between pumps and signals that could be harmful in co-pumped Raman amplification and should be taken into account during the design of Raman amplifiers.