Effect of resonance radiative processes on the amplification factor
  Optimal conditions to acomplish amplification without inversion in three-level schemes based on quantum nonlinear interference effects are analyzed. Specific features of relaxation processes in optical transitions seting these conditions apart from those in microwave schemes are outlined. Numerical evaluations related to neon 2s_2-2p_4-3s_2 transitions are given. 
T. Ya. Popova and A. K. Popov