“…In equation (76), e measures the orientation of a class of pump dipoles with respect to the x axis (which is perpendicular to the pump direction), and cp measures the orientation of the dipoles around the x axis [24,59]. Similar interpretations hold for the gain dipoles in equation (77) and the saturable absorber dipoles in equation (78). The average values of the polarizations induced by the pump and signal fields are given by, (88) These approximations would not always be valid, but they seem to provide adequate agreement with available data.…”