Multisubband infrared dressing of excitons in quantum wells

A formalism is described that self-consistently treats the effects of infrared (ir) coupling fields on the interband quantum-well absorption spectrum when both the $e1-e2\mathrm{}$ and $e2-e3\mathrm{}$ conduction subband transitions are nearly resonant with the ir frequency. For the 8.5-nm-wide GaAs quantum-well samples typically considered for ir dressing studies, we show that the simultaneous two-photon coupling of the $e1-hh1\mathrm{}$ and $e3-hh1\mathrm{}$ excitons and the one-photon coupling of all three excitons produces significantly different results than those obtained when the $e2-e3\mathrm{}$ coupling is neglected. In particular we find that the position and shape of the dominant $e1-hh1\mathrm{}$ exciton feature each change nonmonotonically, and saturate with increasing ir intensity. This is in better agreement with existing experimental results than previous calculations based on simple $e1-e2\mathrm{}$ coupling.