Nonlinear surface photoeffect in multi-color laser field: effect of the finite width of the surface potential barrier

The surface photoeffect in a multi-color laser field with controllable phas e shift between monochromatic components is studied theoretically in the fr ame of a simple analytically solvable model. The total photocurrent appears to be phase modulated due to the interference between the various ionizati on paths indicating the possibility of the coherent phase control of this p henomenon. The dependence of this modulation on the effective width of the surface barrier is under investigation. Corresponding calculations are made for two frequencies of pumping radiation and their second harmonics. It is shown that the complex amplitudes of one- and two-photon processes may dep end significantly on the surface barrier width, especially for high frequen cy. However, the difference amplitude parameters which determine the depth and initial phase of the photocurrent phase modulation are only weak functi ons of the barrier width. Nevertheless, there is some phase shift range in which the phase dependence of the ratio of photocurrent values for differen t barrier widths has sharp features.