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 (χ^<3>) of ZnSe single crystals. It was measured by two independent experimental techniques: third harmonic generation (THG) at 1.907 μm and degenerate four wave mixing (DFWM) at 0.532 μm methods. The results of DFWM measurements show that the third order nonlinear optical susceptibility (χ^<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 (β) of Zn_1-xAg_xSe (x ≤ 0.20) crystals were investigated using the transmission method. The experimental results show that the imaginary part of third order nonlinear optical susceptibility (χ^<3>) decrease with increase of Ag content.