We report a novel method to realize high-aspect ratio (similar to 1000) of submicron size inverted domains in two-dimensional periodically poled lattice structure on 0.5 mm-thick lithium niobate (LiNbO3) substrate. This is achieved by photolithographic patterning of LiNbO3 surface with self-organized dielectric spheres, followed by pulsed-field poling with liquid electrodes. The realization of submicron domain structures on electrically poled LiNbO3 is ascribed to a local modification of the polarization switching field due to the dielectric- and structure-induced discontinuity at the boundary between the photoresist opening and self-organized dielectric spheres. (c) 2006 Elsevier B.V. All rights reserved.