Interband multiphoton magneto- and electro-absorption in semiconductor superlattices

Abstract

Interband optical transitions in a semiconductor superlattice induced by an intense optical wave in the presence of uniform electric and magnetic fields are analysed. Both the oscillating electric field of the optical wave and the uniform magnetic field are directed perpendicular to the heterolayers whilst the uniform electric field is in a direction parallel to the heterolayers. The superlattice potential is modelled by a periodic chain of delta -function-type barriers. Quasi-energetic time-dependent states are used. The explicit dependence of the coefficient of the multiphoton absorption on the frequency and magnitude of the light wave, the superlattice parameters and the magnitudes of the uniform fields is obtained. It is shown that the dynamical Stark effect induced by the strong oscillating electric field leads to a shift of the edge of absorption to shorter wavelengths. The form of magneto-absorption essentially depends upon the parity of the number of absorbed photons and the relationship between the separation of the Landau levels and the total width of the electron and hole minibands. It is found that the main effect of a uniform electric field is to shift the absorption edge to longer wavelengths (the Franz-Keldysh effect).