Measurement of laser-induced refractive index change of inverted ferroelectric domain LiNbO3

Optical nonlinearities of periodically poled LiNbO3 crystals were investigated by the single beam Z-scan technique with a continuous wave (cw) laser beam at 532 nm. The nonlinear optical absorption coefficient and refractive index change are determined to be 8.1 x 10(-6) cm/W and 2.6 x 10(-4) at 0.5 MW/cm(2) light intensity, respectively. Both sign and magnitude of the measured refractive nonlinearity are considerably different from the Z-scan results in congruent LiNbO3. The nonlinearities in the periodically poled LiNbO3 induced by 532 nm continuous waves are believed to be mainly due to the photorefractive effect. (C) 2007 Optical Society of America.