Excitons in resonant coupling of quantum wells

We examine, experimentally and theoretically, the effects of excitons in optical measurements of resonant coupling of quantum wells. We find that the exciton line splittings do not correspond directly to the underlying electron levels, which leads to differences in the bias fields for resonance of, e.g., {~}10%. We construct a variational model of excitons in coupled wells and successfully compare this model with measured splittings near the resonance between the first and second electron levels of adjacent wells, deducing the actual conditions for coupling of the ``bare'' electron levels.