We report the formation of directionally ordered nano-scale surface domains on the +z face of undoped congruent lithium niobate single crystals by using UV illunmination through a phase mask of sub-micron periodicity with an energy fluence between similar to 90 mJ/cm(2) and 150 mJ/cm(2) at lambda = 266 nm. We clearly show here that the UV-induced surface ferroelectric domains only nucleate at and propagate along maxima of laser intensity. Although the domain line separation varies and is greater than 2 mu m for this set of experimental conditions, this enables a degree of control over the all-optical poling process. (c) 2006 Elsevier B.V. All rights reserved.