Abstract
We predict strong spin-polarization switching of the photocurrent signal obtained from a single, self-assembled quantum dot photodiode by tuning only the intensity of elliptically polarized light. In the nonlinear mechanism described here, elliptically polarized light creates an effective exchange channel between different exciton spin states through the biexciton state, as we demonstrate by both numerical and analytical methods. This effect can be used as a dynamical switch to invert the spin polarization of the extracted photocurrent. We further show that the effect persists in realistic ensembles of dots, making this a powerful technique to dynamically generate spin polarized electron currents.
- Received 21 July 2006
DOI:https://doi.org/10.1103/PhysRevB.75.155334
©2007 American Physical Society