ANISOTROPIC OPTICAL MATRIX-ELEMENTS IN [HHK]-ORIENTED QUANTUM WIRES

Optical polarization properties in quantum wires (QWIs) are theoretica lly investigated as functions of wire crystallographic directions taki ng the valence band anisotropy into account. Optical matrix elements a nd gain spectra are calculated for GaAs cylindrical QWIs with infinite barriers. It is shown that the optical matrix element for light polar ized to the wire direction shows weak dependence on the wire crystallo graphic direction. In contrast, the valence band anisotropy causes str ong dependence on the wire direction for light polarized to the perpen dicular directions, and large in-plane optical anisotropy appears for [110]- and [112]-oriented QWIs. It is considered, from the calculated results of the gain spectra, that a [111]-QWI laser shows the lowest t hreshold current and that the [1, - 1,0]-QWIs on a (110) substrate are the most suitable for polarization controlled vertical cavity surface emitting lasers. These results indicate that the structural optimizat ion from the viewpoint of the crystallographic direction is important for optical devices using QWIs.