Figure 1: (a) Ultimate signal gain (dashed curves) and optimal amplifier length (solid curves) plotted as functions of 𝜏 𝑐 for an SRA operating in the undepleted-pump regime when 𝑆 𝑠 = 𝑆 𝑝 = 1 ; different colors correspond to different values of 𝛼 𝑠 = 𝛼 𝑝 𝛼 . (b) Input and output pump intensities calculated as a function of 𝜏 𝑐 using (10) with 𝑆 𝑝 = 1 . Refer to text for other parameters.