Abstract

Large field-induced optical absorption and refractive index variations through the quantum confined Stark effect in quantum well structures have prompted the development of many high performance compact optical modulating devices¹⁾. However, several shortcomings are present and one of them is a strong polarization dependent characteristic in lattice-matched systems²⁾. This is due to the fact that the dipole moments of electron-heavy/light hole transitions show a strong polarization dependence, such that while TE mode light, with the electric vector parallel to the quantum well layers, interacts with both heavy and light hole transitions, only electron-light hole transitions are involved in the TM mode polarization, where the electric vector is perpendicular to the quantum well layers³⁾. Moreover, in an unstrained quantum well, the valence bands for the heavy and light holes are degenerate and hence the electron-heavy hole transition always lead the electron-light hole transition at the absorption edge due to the heavy hole’s larger effective mass. As a result, there exists a large difference in the optical absorption and refractive index variation at the absorption edge between the TE and TM mode polarizations.

© 1993 Optical Society of America