Polarization Ellipticity of Micro-photoluminescence in a Single GaAs/AlGaAs Quantum Ring

Abstract

The polarized micro-photoluminescence spectrum was analyzed to investigate the anisotropic localized states in a single GaAs quantum ring. An energy difference of similar to 0.1 meV was observed from the perpendicularly polarized spectrum measured by a pair of linear analyzers. Spectral dependence of the polarized emission was also characterized in terms of rotation and ellipticity angles using four Stokes parameters. While the rotation angle indicates the symmetric axis of an anisotropic quantum ring with a small variation (+/- 2 degrees), the ellipticity angle varies from 7.4 degrees down to -2.5 degrees. We conclude that optical anisotropy and birefringence are induced by the crescent-like lateral shape of localized states.