  We describe a technique for surface domain engineering in congruent lithium
niobate single crystals. The method is based on conventional electric-field
poling, but involves an intentional overpoling step that inverts all the
material apart from a thin surface region directly below the patterned
photoresist. The surface poled structures show good domain uniformity, and the
technique has so far been applied to produce domain periods as small as 1 \mu
m. The technique is fully compatible with nonlinear optical integrated devices
based on waveguide structures.
