Photocurrent, electroluminescence,\ and photoluminescence spectroscopy were used for the characterisation of laser structures containing ultrathin InAs delta-layers in GaAs matrix surrounded for AlGaAs waveguide and grown by low-pressure metal organic vapour phase epitaxy. Three types of delta-layer structures for laser active layers were investigated: single layers with different thickness (W-L) different numbers of identical layers (N), and seven identical delta-layers separated by GaAs spacers of variable thickness (S-L). Measurement revealed two fundamental optical transition between electron and heady and light hole states in the delta-layers, Both transitions are shifted to lower energies by hundreds of meV when W-L and N increases or S-L decreases. While the effect of W-L can be explained by a quantum model accounting for the influence of stress and quantum state coupling, data obtained from multilayer structures exhibit significant deviation from theory. (C) 2003 Elsevier Science B.V. All rights reserved.