  The electronic structure of strain-engineered single InGaAs/GaAs quantum dots
emitting in the telecommunication O band is probed experimentally by
photoluminescence excitation spectroscopy. Observed resonances can be
attributed to p-shell states of individual quantum dots. The determined energy
difference between s-shell and p-shell shows an inverse dependence on the
emission energy. The experimental data are compared with the results of
confined states calculations, where the impact of the size and composition in
the investigated structures is simulated within the 8-band
$\mathbf{k}\cdot\mathbf{p}$ model. On this basis, the experimental observation
is attributed mainly to changes in indium content within individual quantum
dots, indicating a way of engineering and selecting a desired quantum dot,
whose electronic structure is the most suitable for a given nanophotonic
application.
