Pseudo-metal reflection at the interface between a linear and a nonlinear material

We study theoretically the reflectivity variation of a light wave at the interface between a linear material and a quadratic nonlinear material, upon simultaneous incidence of a wave at the second harmonic frequency overlapped with the first one. The presence of the phase-coherent second harmonic wave results in a phase dependent modification of the effective complex linear susceptibility of the nonlinear medium. Depending on the phase difference between these beams different phenomena occur. Pseudo-metal reflection occurs when there is a net transfer of photons from one wave to the other, whereas modified Fresnel reflection takes place when there is no net transfer of photons. (C) 1997 Elsevier Science B.V.