Nonlinear optical rectification and optical absorption in GaAs-Ga1-xAlxAs double quantum wells under applied electric and magnetic fields

In this work are studied the electron-related nonlinear optical absorption and nonlinear optical rectification in GaAs-Ga1-xAlxAs asymmetric double quantum wells under applied electric and magnetic field. The density matrix formalism and the effective mass and parabolic band approximations have been considered. The main findings show that in asymmetrical heterostructures under an appropriate strength of the electric field it is possible that the optical rectification is zero and in such circumstances the optical absorption has a relative maximum; similar behavior is observed in these optical properties as a function of the length of one of the two quantum wells and without applied electric field. Also, the results suggest that in asymmetric double quantum wells the optical absorption is a nonmonotonic increasing (decreasing) function of the applied magnetic field (width of the central barrier) and that particularly when the optical absorption has an inflection point the optical absorption has an absolute maximum. Finally we found that the resonant peaks in the nonlinear optical rectification and nonlinear optical absorption can be red-shifted to low photon energies or blue-shifted to large photon energies depending on the energy difference of the two lowest confined states in the heterostructure, and this condition can be controlled by changes in the external proofs such us applied electric and magnetic fields or by changes in the structural dimensions of the coupled quantum well system. (C) 2011 Elsevier B.V. All rights reserved.