Observation of Dynamical Franz-Keldysh Effect

Abstract

We observe the linear and non-linear optical properties of a semiconductor multiple quantum well under intense terahertz irradiation to reveal a Dynamical Franz-Keldysh Effect. It is characterized by increased sub-gap absorption and oscillations in the absorption above the gap which vary with applied THz field and frequency. We also observe non-linear mixing of near-bandgap light of frequency ΩNIR with a strong Terahertz field of frequency ωTHz to produce optical sidebands at frequencies ΩNIR ± 2nωTHz. We discuss our results as a function of THz field and frequency, and compare them to our theoretical model.