Optical properties of AlxInyGa1-x-yAs/AlzGawIn1-z-wAs quantum wells under electric and magnetic fields for telecommunication applications

In this paper, we have designed AlxInyGa1-x-yAs/AlzGawIn1-z-wAs quantum well structure having absorption at the telecom band of 1.55 mu m. Interband absorption coefficients have been calculated under applied electric and magnetic fields. First, electronic band structure and corresponding energy states for electrons, heavy holes and light holes in the conduction and valance bands have been obtained by solving the one-dimensional time-independent Schrodinger equation. The effects of the electric and magnetic fields on the electron energy levels have been investigated using the finite element method under the effective mass approximation. The magnetic field, which bends band edges, has no major effect on the localization of the electronic states. On the other hand, the electric field causes the localization of all electronic states in different quantum wells. It has been observed that many interband transitions are possible without applied electric and magnetic fields. Absorption occurs from heavy (light) holes to electron states. This causes uncontrolled (undirected) absorption of photon energy between the energy levels. When the electric field is applied, it significantly affects the absorption coefficient and the absorption coefficient values of e(1)-hh(2), e(2)-hh(1), e(2)-hh(3), e(2)-lh(1), e(2)-lh(3), e(3)-hh(2) and e(3)-lh(2) cross out due to very sharp decrease in the dipole moment matrix elements but e(1)-hh(1), e(1)-lh(1) and e(3)-lh(3) transitions have emerged and become very strong at 20 kV/cm electric field intensity. The magnetic field causes a negligible small decrease in the optical absorption coefficient. The e(1)-hh(2) transition vanishes due to zero dipole moment matrix elements. As compared to the electric field, the magnetic field is not usable for single-wavelength absorption.