THICKNESS DEPENDENCE OF THE PHASE-CONJUGATE SIGNAL OF AMORPHOUS SELENIUM THIN-FILMS

The dependence of the phase conjugate (PC) signal on the thickness of the nonlinear medium has been studied for amorphous selenium thin film samples, in the range from 1500 to 48000 Angstrom. The experiments we re performed using a degenerate four wave mixing (DFWM) scheme. The PC signal increases with thickness of the sample in the 1500-15000 Angst rom range, for thicker samples the PC signal reaches a saturation valu e. The results are analyzed using a DFWM model in absorbing media. A n ovel theoretical treatment where the effect of reflection at the air-f ilm interface plays a dominant role yields good agreement with the exp erimental data.