Nanjing 210093, People's Republic of China

ABSTRACT It was found that the ferroelectric coercive field ofLiNbO3, both in forward and reverse direction,vary with time after domain inversion. The existence of an internal field decaying as et is proposed,and the related coefficients are fitted.Keywords: ferroelectric domain inversion, ferroelectric coercive field, QPM-SHG 1 . INTRODUCTION Lithium niobate (LiNbO3) is an attractive ferroe1ectric material for modern optoelectronic device applications due to its low propagation loss, large electro-optic and nonlinear optical frequency doubling coefficients. In recent years, there has been an increasing interest in quasi-phase-. matching(QPM) technique with periodical inversion of ferroelectric domain in LiNbO3, because ofwidespread use of this technique in application covering second-harmonic generation (SHG), the difference frequency generation (DFG) of infrared, squeezed light generation for optical communication, and so on. Several methods have been developed for ferroelectric domain reversal inbulk LiNbO3. Among these techniques, the electric field poling method arouses much interest andthere are extensive studies on fabrication, characterization, and performance of periodically poledLiNbO3 by applying this method13. However, to our knowledge, the work concerning basic materialproperties of LiNbO3 during the domain inversion process is still lack.Recently, Chao et al. found the time-dependent ferroelectric coercive field after domain inversionin LiTaO3 crystal.4 The existence of an net time-varying internal field was postulated to account forthis phenomenon. In this paper, we report our studies on time dependence of the ferroelectric coercivefield after domain inversion in LiNbO3 crystal.