A systematic study on the role of each growth parameter in the PPLN period and the modification of the domain width across the crystal due to the growth process is presented. We focus our attention to the effect of the random errors in the domain boundary position on the SHG conversion efficiency and show a way of optimizing the growth process in order to achieve the highest SHG conversion efficiency and to establish the tolerances on the fabrication processes. (C) 2002 Elsevier Science B.V. All rights reserved.