  We theoretically study the intraband transition spectrum of single electron
transistors (SETs) composed of individual self-assembled quantum dots. The
polarization of SETs is obtained by using the nonequilibrium Green's function
technique and the Anderson model with three energy levels. Owing to
nonradiative coupling between two excited states through the continuum of
electrodes, the Fano interference effect significantly influences the peak
position and intensity of infrared wavelength single-photon spectrum.
