We consider nonlinear selective reflection on the interface between dielectric media and dilute vapors of three-level atoms. Assuming a pump-probe scheme with cascade-type excitation, we study the modification ΔR of the reflection coefficient of the probe induced by the presence of the pump. We extend previous calculations of the frequency spectrum of ΔR made for low probe power to the case of arbitrary probe power. One then obtains a strong resonance which has already been observed experimentally. Moreover, for the two-photon resonance present in the low-intensity spectrum, a power splitting can be predicted with increasing intensity © 1996 The American Physical Society.

• Received 15 September 1995

DOI:https://doi.org/10.1103/PhysRevA.53.3647