The blue shift of metalorganic vapor phase epitaxy grown 1.3 mu m InGaAs quantum dot (QD) emission wavelength during stacking and overgrowth is investigated. Defect generation in the vicinity or with the QD layers is identified as the major source for the blue shift of the photoluminescence. Defect reduction by optimisation of growth parameters leads to efficient suppression of the blue shift. Thereby, 6-fold stacked InGaAs QD laser structures with negligible blue shift of only 20 nm are realized at 1.3 mu m wavelength. First devices emit at 1281 nm exhibiting threshold current densities of 600 A/cm(2). (C) 2008 Elsevier B.V. All rights reserved.