Rabi splitting of the optical intersubband absorption line of multiple quantum wellsinside a Fabry-Pérot microcavity

In a nonlocal semiclassical local-field approach and by using a simple one-band model in which the conduction-band nonparabolicity is taken into account in an energy-dependent effective-mass scheme, we have derived a rigorous expression for the p-polarized optical intersubband absorption coefficient of a multiple-quantum-well (MQW) structure inside an asymmetric Fabry-Pérot microcavity. For a GaAs/${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As MQW structure sandwiched between a GaAs/AlAs distributed Bragg reflector and vacuum, we performed numerical calculations of the optical-absorption spectra for different parameters such as the cavity length, the angle of incidence, the electron concentration, and the number of quantum wells (QW's) in the structure. In the strong-coupling regime, our results show that the so-called Rabi splitting of the absorption spectrum, which is due to the electromagnetic interactions between the cavity modes and the intersubband modes, is increased in size with an increase in the QW number and in the sheet electron density. The contrast of the splitting is also found to be strongly dependent of these parameters. Finally, it is demonstrated that the Rabi splitting of the intersubband absorption line can be easily tuned by varying either the cavity length or the angle of incidence.