Highly ordered three-dimensional periodic arrays of In0.40Ga0.60As quantum wires (QWRs) on GaAs (311)A and GaAs (331)A have been achieved by molecular beam epitaxy and revealed by high-resolution X-ray diffraction. Polarization dependent photoluminescence measurements demonstrated high optical anisotropy of 40% in (331)A QWRs and 16% in (311)A QWRs. Such a difference in polarization value could be caused by the differences in geometry, ordering, and high piezoelectric field between (331)A and (311)A samples. (C) 2011 Elsevier B.V. All rights reserved.