Optical orientation of electron spins by linearly polarized light
  Absorption of circularly polarized light in semiconductors is known to result in optical orientation of electron and hole spins. It has been shown here that in semiconductor quantum well structures spin orientation of carriers can be achieved by linearly or even unpolarized light. Moreover, the sign and magnitude of the spin orientation can be varied by rotating the polarization plane of incidence light. The effect under study is related to reduced symmetry of the quantum wells as compared to bulk materials and, microscopically, caused by zero-field spin splitting of electron and hole states. 
S.A. Tarasenko