Relative intensity noise (RIN) reduction in fiber-based Raman amplifier systems

An arrangement for reducing the effects of pump signal relative intensity noise (RIN) in a Raman fiber amplifier. A portion of the output from a pump laser source is applied as an input to a compensating, lower power laser module, where fluctuations in the output power of the pump laser are used to control the bias current applied as an input to the compensating laser such that as the pump power increases, the bias current (and lower power laser output) decreases; conversely, as the pump power decreases, the bias current applied as an input to the compensating laser will be increased. The result is a relatively flat gain as seen by the information signal, thus minimizing the transfer of relative intensity noise from the pump to the signal.