Interaction of a multi-color optical field with a THz-driven quantum well

Summary form only given. An optical beam tuned at an interband transition of a quantum well (QW) experiences absorption. The degree of the absorption can be controlled by applying a bias field across the QW via quantum-confined Stark effect (QCSE). However, if the bias field changes very rapidly (in the THz range), the optical absorption becomes quite different from the usual QCSE. In particular, for QWs with strong excitonic properties, the application of THz field results in the appearance of strong absorption peaks not only at the energy of the usual excitonic transition but also at energies separated from it by a multiple of the THz frequency. For THz-driven QWs, the phase between the spectral components separated by a multiple of the THz frequency plays a significant role. To illustrate the role of the phase, we studied optical absorption in a 150 /spl Aring/ GaAs QW using the semiconductor Bloch equations in the linear regime with respect to the optical field strength. The effects of the THz field are treated nonperturbatively. The calculated strong phase dependence of the optical absorption in THz-driven QWs may open new possibilities for optical switching in WDM systems.