Effect of enhancing the Raman gain factor on the linearity of Raman fibre amplifiers

The effect of enhancing the Raman gain factor on the linearity characteristics of Raman fibre amplifiers is analysed. In addition to providing higher Raman gain per unit pump power, a higher value for the Raman gain factor also results in a lower value for the maximum gain, and therefore the maximum output power, available from the amplifier if it is to operate in the linear regime. This has important implications for optimising the design of Raman fibre amplifiers.