Resonant coupling between metal surface plasmons and intersubband plasmons and its manifestation in attenuated total reflection spectra

Resonant coupling between metal surface plasmons (MSP's) and intersubband plasmons (IP's) excited in metal-multiple quantum well-dielectric structures is discussed theoretically, taking into account the retardation effects. The nonradiative electromagnetic modes of the structures have been calculated modeling a multiple quantum well slab by a uniform uniaxial effective medium. The results obtained indicate that in the frequency region of intersubband excitations hybrid MSP-IP-photon modes are formed. We demonstrate that, in general, the normal-mode spectrum consists of two sets of branches separated by a gap. The manifestation of the hybrid modes in attenuated total reflection spectra is considered in detail.