Phase and amplitude control of optical bistability in the three-coupled quantum wells

We investigate the optical properties of a weak probe field in a ladder-type configuration in an asymmetric semiconductor three-coupled quantum well system. It is shown that the dispersion, absorption and optical bistability behavior of the system can be controlled by both the amplitude and relative phase of applied fields. The phase dependence arises from a scattering of the pumping and signal fields into the probe field mode at a frequency which in multi-photon resonance condition is the same as the probe field frequency. Moreover, it is demonstrated that in the gain region of the absorption spectrum, considerable output is obtained for zero input.