Intersubband optical absorption in coupled quantum wells under an applied electric field

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Abstract
The very large tunability of the transition energy when an electric field is applied is found in the intersubband optical transition in two strongly coupled semiconductor quantum wells. The energy of the absorption peak can shift to red or blue and is very sensitive to the electric field, in contrast to the single-well case, which has only a small blue shift. The oscillator strengths and the selection rule depend on the degree of coupling and are quite different from the single-well case. The method we use to characterize the energy levels and the wave functions of the coupled quantum wells has several advantages over the previous theoretical calculations in that the effective-mass difference, the finiteness of the barrier height, and arbitrary structure of the quantum wells can be taken into account by using a transfer-matrix technique.