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We have theoretically studied the field-dependent optical properties of a step quantum-well structure, which consists of a small well inside a big well. The wave functions of the small and big wells overlap and their eigenenergies have different field dependencies. The transition from a small-well state to a big well state thus gives a large Stark shift at low applied field without degrading the oscillator strength. Another advantage is to allow optical transitions that are forbidden in simple single-well structures. This relaxation of the selection rule makes it possible to provide optical pumping for intersubband lasing. Also, since the step well is asymmetric, many nonlinear properties are expected.
Yuh et al. (Thu,) studied this question.