Elliptical Polarization of Localized States in an Anisotropic Single GaAs Quantum Ring.

Localized states in an anisotropic single GaAs quantum ring were investigated in terms of polarization dependence of micro-photoluminescence spectrum at 5K. Given four Stokes parameters measured with a pair of linear polarizers and waveplates, the elliptical polarization states of two different vertical confinement states ( k = 1 and k = 2 ) were compared with phase, rotation, and ellipticity angles. While the polarized emission intensity of the k = 2 states becomes enhanced along [1,1,0] compared to that along [1, 1 ¯ ,0], the polarization asymmetry of the k = 1 states shows the opposite result. We conclude the polarization state is determined by the shape of the lateral wavefunctions. In the k = 2 state, crescent-like wavefunctions are strongly localized, but the k = 1 state consists of two crescent-like wavefunctions, which are connected weakly through quantum tunneling. [ABSTRACT FROM AUTHOR]