Third-order nonlinear optical properties of new dithienylethylenes

We report the measurement of the third-order susceptibilities of new dithienylethylenes in solutions using the degenerate four wave mixing technique at λ=532 nm in picosecond regime. From these measurements we deduced the values of second order hyperpolarizabilities γ, which are about 103 larger than the γ value of CS2. We determined also the optical power limiting properties of the mentioned compounds. The measurements were made using nanosecond laser pulses in the visible range. The dispersion of nonlinear absorption coefficients is obtained in the framework of gaussian collimated beam propagation in sample.