Quadratic Solitons in Negative Refractive Index Medium
  We are considered the propagation of the fundamental and second harmonic solitary waves under the slowly varying envelope pulses approximation in a quadratic nonlinear medium that characterized by negative refraction index at the frequency of fundamental wave and by positive refractive index at the second harmonic frequency. We find the some solutions of the evolution equations which described the steady state simulton, coupled second harmonic and fundamental frequency waves propagation in this materials. 
Andrew I. Maimistov, Ildar R. Gabitov, Elena V. Kazantseva