  In this Letter we show how a single beam optical trap offers the means for
three-dimensional manipulation of semiconductor nanorods in solution.
Furthermore rotation of the direction of the electric field provides control
over the orientation of the nanorods, which is shown by polarisation analysis
of two photon induced fluorescence. Statistics over tens of trapped
agglomerates reveal a correlation between the measured degree of polarisation,
the trap stiffness and the intensity of the emitted light, confirming that we
are approaching the single particle limit.
