Abstract

A scheme is proposed to achieve optical bistability through the interaction of CO₂ laser radiation with a system of asymmetric coupled quantum wells. The system of interest consists of layers of GaAs and Al_xGa_1-xAs with different Al-content as shown in Fig. 1. The absorptive properties of this nonlinear medium are analyzed by solving self-consistently Schrödinger’s and Poisson’s equation together with a set of rate equations for the occupation of the three lowest subbands. Resonant excitation of the 1–3 intersubband transition causes transfer of electrons into the narrow quantum well, and, hence a self-consistent shift of the energy levels.^[1] if the laser is tuned slightly above resonance, the 1-3 energy separation is pushed into resonance with increasing pump intensity. This leads to absorption increasing with intensity and provides a nonlinear mechanism resulting in intrinsic optical bistability.^[2]

© 1992 IQEC