Optical reflection from long-period multiple quantum wells: effects of dielectric constant mismatch

The theory of resonant optical reflection from long-period multiple quantum-well structures has been extended to take into account the difference between the dielectric constant of the barrier, e b , and the nonresonant contribution, e a , to the dielectric function in the wells. The reflection spectra taken from CdTe/CdMgTe quasi-Bragg quantum wells reveal, in addition to sharp excitonic features, smooth interference fringes determined by the mismatch e a ≠ ϵ b . Implications arising due to the dielectric constant mismatch as well as due to detuning from the resonant Bragg condition are analyzed and discussed.