We have investigated the structural and optical properties of multi-stacked self-organized InAs quantum dot (QD) structures on InP (3 1 1)B substrates grown by molecular beam epitaxy. The reciprocal space mapping measured for asymmetric (4 0 0) reflections in high resolution X-ray diffraction revealed that satellite peaks originating from a periodic structure were not only observed along the growth direction, but also along [(2) over bar 3 3] direction within each QD plane. The mean in-plane spacing of neighboring QDs was 97 nm, which was in good agreement with direct measurement of 100 nm by using atomic force microscope. A superior three-dimensional QD superlattice with a total density of 10(12) cm(-2) was achieved by our growth technique. We also observed a strong photoluminescence emission at 1.55 mu m with a narrow linewidth of 56.07 meV at room temperature. (c) 2006 Elsevier B.V. All rights reserved.