Intensity dependent index guiding in a seeded Raman amplifier

This paper examines the effect of index guiding in a Raman amplifier. The slowly varying Maxwell wave equation including the total Raman susceptibility for a seeded Raman amplifier is explored. Numerical calculations indicate that the real part of the Raman susceptibility cause the Raman medium to act as a lens when the Stokes seed is detuned from the Raman resonance. This focusing effect leads to a gain enhancement of up to 5% and a shift in the peak Stokes energy by up to 145 MHz to the blue side of the Raman resonance for Raman scattering in H2 with a pump laser at 532 nm and an input seed near 683 nm.