OPTICAL REFLECTION FROM LONG-PERIOD MULTIPLE-QUANTUM WELLS - EFFECTS OF DIELECTRIC-CONSTANT MISMATCH

The theory of resonant optical reflection from long-period multiple qu antum-well structures has been extended to take into account the diffe rence between the dielectric constant of the barrier, epsilon(b), and the nonresonant contribution, epsilon(a), to the dielectric function i n 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 epsilon(a) not equal epsilon(b). Implications arising due to the dielectric constant mismat ch as well as due to detuning from the resonant Bragg condition are an alyzed and discussed. (C) 1998 Elsevier Science B.V. All rights reserv ed.