Conspicuous influence of hole-subband mixing on Fano-resonance profiles of excitons in a wide quantum well

Photoabsorption spectra of an exciton in a wide quantum well are investigated based on the $4\times 4$ Luttinger Hamiltonian. High-resolution calculations of Fano profiles with natural spectral widths are implemented over an extensive energy region by solving the multichannel scattering equations using the R-matrix propagation method. The resulting spectral profiles are compared with those with excluding an effect of hole subband mixing. This effect gives rise to a conspicuous change of absorption spectra, especially, inversion of a peak-and-dip structure in asymmetric profiles for optically active excitons. Moreover, distinct asymmetry is seen in profiles for optically inactive excitons due to the hole subband mixing, not to Coulomb coupling.