Picosecond Z-scan study of bound electronic Kerr effect in LiNbO3 crystal associated with two-photon absorption

Abstract

The third-order optical nonlinearities in LiNbO3 crystal have been measured using Z-scan technique with picosecond pulses at 532 nm. The nonlinear absorption coefficient and nonlinear refractive index are determined to be 2.5 × 10-10 cm/W and 5.3 × 10-15 cm2/W, respectively. Both sign and magnitude of the measured refractive nonlinearity are considerably different from the reported Z-scan results in LiNbO3 obtained with cw laser beam at 514 nm. The nonlinearities in LiNbO3 induced by 532 nm picosecond pulses are believed to be mainly due to two-photon absorption and bound electronic Kerr effect associated with the two-photon absorption.