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HL: Halbleiterphysik

HL 49: Poster II

HL 49.65: Poster

Donnerstag, 27. März 2003, 16:30–19:00, HSZ/P2

Polarization resolved single dot spectroscopy — •M. Schardt¹, R. Dorn², S. Quabis², and G. H. Döhler¹ — ¹Inst. for Technical Physics I — ²Inst. for Optics, University of Erlangen-Nuremberg, Germany

Recent electrooptical investigations of self-assembled InAs quantum dots (SADs) in waveguide-geometry have shown polarization anisotropy due to lighthole transitions [1]. However, the obtained transmission spectra are inhomogeniously broadened due to the large number of SADs embedded in the waveguide-structure. To address a single dot, a vertical incidence is typically chosen. In this configuration, the lost information on the polarization (no TM-mode!) can be gained by a specially designed light beam [2]:

Focusing a radially polarized laser beam through a microscope-objective with high numerical aperture (NA ≥ 0.9) yields in a strong component of the electrical field vector solely along the optical axis at the focal tail (TM). Changing the polarization of the laser beam from radial to azimuthal results in a focus with electrical field vector lying in the focal plane (TE). The resulting spot size is much smaller than predicted by classical diffraction theory, making such a setup a desireable tool for polarization resolved single dot spectroscopy.

[1] O. Wolst et al., Physica E 13 (2002) 283-288

[2] S. Quabis et al., Optics Communications 179 (2000) 1-7