Inter-dot interaction in an array of elliptical quantum dots

We have investigated arrays of quantum dots with elliptical confinement potential on modulation-doped GaAs heterostructures. A laterally structured gate electrode allowed us to tune the system from small isolated dots to large overlapping dots. In far-infrared transmission experiments, we find that the frequency gap between the two resonances with orthogonal linear polarization, which exist in elliptical dots, first decreases and then, very surprisingly, increases again.