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 n(2), nonlinear absorption coefficient beta, magnitude of effective third order susceptibility chi((3)), the second order hyperpolarizability gamma(h) and the coupling factor rho have been estimated. The experimentally determined values of beta, n(2), Re chi((3)) and Im chi((3)), gamma(h) and rho of the compound UP are 2.146 cm/GW, -1.258 x 10(-11) esu, -1.347 x 10(-13) esu, 0.377 x 10(-13) esu, 0.69 x 10(-32) esu and 0.28, respectively. The compound exhibits good optical limiting at 532 nm with the limiting threshold of 80 mu J/pulse. Our studies suggest that compound UP is a potential candidate for optical device applications such as optical limiters. (C) 2011 Elsevier Ltd. All rights reserved.