Kerr nonlinearity enhancement by double tunnelling from quantum dot nanostructure

A model of the dynamical equations of the density matrix describes double tunnelling between double quantum dot (QD) system states, this is to study Kerr nonlinearity in QD structure. Inhomogeneity in the QD system is included which is not included in earlier studies of Kerr nonlinearity in QDs. Possibilities of subluminal and superluminal light propagation and switching between them are examined. Double tunnelling is shown to obtain giant Kerr dispersion compared with single tunnelling. High conduction- and low valence-band tunnelling components are required to obtain high Kerr dispersion. Working with one tunnel component reduced Kerr dispersion and switching between subluminal and superluminal can be obtained and the EIT window can be removed.