Nonlinear Franz–Keldysh effect: two-photon absorption in a semiconducting quantum well

Abstract

Two-photon absorption (TPA) in a semiconducting quantum well (QW) is investigated theoretically in the presence of the electric field. Numerical results show that the TPA depends strongly on the relative orientations of the electric field, the direction of optical polarization, and the direction of carrier confinement in the QW. The TPA is finite at photon energy below the threshold energy where the TPA would vanish in the absence of the electric field for any case. The TPA is large when the electric field is along the direction of carrier confinement in the QW. Moreover, when the electric field is in the plane of the QW, the difference Δα between the TPAs in a finite electric field and in zero field at the threshold energy increases almost linearly with increasing the electric field. In addition, it is also found that, in all cases, the TPA is less in the QW than that in the bulk.