χ(3) measurement and optical limiting studies of urea picrate

The molecular charge complex urea picrate (UP) was synthesized and its third order nonlinear optical properties have been investigated using a single beam Z-scan technique with nanosecond laser pulses at 532 nm. Open aperture data of the compound indicates two photon absorption at this wavelength. The nonlinear refractive index n2, nonlinear absorption coefficient β, magnitude of effective third order susceptibility χ(3), the second order hyperpolarizability γh and the coupling factor ρ have been estimated. The experimentally determined values of β, n2, Re χ(3) and Im χ(3), γh and ρ of the compound UP are 2.146 cm/GW, −1.258×10−11 esu, −1.347×10−13 esu, 0.377×10−13 esu, 0.69×10−32 esu and 0.28, respectively. The compound exhibits good optical limiting at 532 nm with the limiting threshold of 80 μJ/pulse. Our studies suggest that compound UP is a potential candidate for optical device applications such as optical limiters.