LAUSR

Perfect spin precession in a two dimensional electron gas is thea#13; basis of the Datta-Das spin field effect transistor. However, in aa#13; two dimensional system this ideal spin precession can be washed outa#13; by the intersubband mixing effects induced by the Rashba spin-orbita#13; interaction. Here we propose by applying an off-resonant linearlya#13; polarized light a perfect spin modulation of conductance can bea#13; demonstrated in a two dimensional spin field effect transistor. Thisa#13; is because in a two dimensional electron gas due to thea#13; renormalization of the Rashba spin-orbit coupling strength and thea#13; hopping amplitude by the light, the intersubband mixing effects cana#13; be weakened. For an appropriate intensity of the light, thea#13; intersubband mixing effects are completely suppressed. Thesea#13; phenomena provide a promising way to design an optically-controlleda#13; spintronics device.