Long wavelength enhanced Kerr nonlinearity via Fano-type interference in semiconductor quantum wells

The linear and nonlinear behaviors of susceptibility via tunable Fano-type interference, based on intersubband transitions in asymmetric double quantum wells (QWs) driven coherently by a probe laser field, are analyzed. It is shown that Kerr nonlinearity can be controlled competently by tuning the energy splitting of the two excited states (the coupling strength of the tunneling), i.e. Fano-type interference. This outcome may be used for optimizing and controlling long wavelength optical switching processes in QW solid-state systems, which is much more useful than that currently used in atomic systems because of its flexible design and the controllable interference strength.