In this paper, we propose here an alternative technique based on interferometric imaging microscopy, which was introduced recently for the examination of individual nanoscale ferroelectric crystals with an homogeneous domain apply this technique for the first time, in order to investigate the domain structure in both cases of periodically and aperiodically poled crystalline structures. We experimentally demonstrate the ability of this approach to characterize crystals embedding inverted domains down to diffractionlimited resolution. | LASER amp PHOTONICS REVIEWS Laser Photonics Rev. 9 No. 2 214 223 2015 DOI Abstract The ferroelectric domain structures of periodically poled KTiOPO4 and two-dimensional short range ordered poled LiNbO3 crystals are determined non-invasively by interferomet- ric measurements of the electro-optically induced phase retar- dation. Owing to the sign reversal of the electro-optical coeffi- cients upon domain inversion a π phase shift is observed for the inverted domains. The microscopic setup provides diffraction- limited spatial resolution allowing us to reveal the nonlinear and electro-optical modulation patterns in ferroelectric crys- tals in a non-destructive manner and to determine the poling period duty cycle and short-range order as well as detect lo- cal defects in the domain structure. Conversely knowing the ferroelectric domain structure one can use electro-optical mi- ORIGINAL croscopy so as to infer the distribution of the electric field therein. PAPER Electro-optical interferometric microscopy of periodic and aperiodic ferroelectric structures Duc Thien Trinh1 3 Vasyl Shynkar1 Ady Arie2 Yan Sheng4 Wieslaw Krolikowski4 5 and Joseph Zyss1 1. Introduction addition the results of surface measurements are not al- ways simple to analyze 8 . Optical techniques based on Nonlinear crystals in which the sign of the nonlinear coeffi- interferometry 9 the electro-optical effect 10 and non- cient is spatially modulated are widely used to obtain quasi- linear optics 11 12 permit us to solve many of these phase-matched nonlinear interactions 1 2 . The modula- drawbacks. In particular optical methods are non-invasive tion of the nonlinear coefficient in ferroelectric crystals can allowing for in-situ measurements and three-dimensional be achieved by the electric field poling technique 3 in 3D domain-structure characterization. Moreover they which a series of electric pulses that are applied through pat- are less time consuming and provide more .
