It is well known by those practicing the techniques of nonlinear optics that the power that may be generated in a frequency summing process and the gain that may be obtained in a parametric process are determined by the interaction of tire nonlinear and linear susceptibilities. In general as an atomic transition to the ground state is approached, the nonlinear susceptibility is resonantly enhanced, but at the same time the media exhibits a rapidly increasing refractive index and becomes opaque.