Influence of Ag content on third order nonlinear optical susceptibility of ZnSe single crystals

We have investigated the influence of the Ag content on third order nonlinear optical susceptibility (/spl chi//sup <3>/) of ZnSe single crystals. It was measured by two independent experimental techniques: third harmonic generation (THG) at 1.907 /spl mu/m and degenerate four wave mixing (DFWM) at 0.532 /spl mu/m methods. The results of DFWM measurements show that the third order nonlinear optical susceptibility (/spl chi//sup <3>/) decreases with the increase of the Ag content. The results of THG and DFWM will be correlated via multilevel quantum models. Also the two photon absorption coefficient (/spl beta/) of Zn/sub 1-x/Ag/sub x/Se (x /spl les/ 0.20) crystals were investigated using the transmission method. The experimental results show that the imaginary part of third order nonlinear optical susceptibility (/spl chi//sup <3>/) decrease with increase of Ag content.