Spin coherence in semiconductor heterostructures

The addition of the spin degree of freedom to the nonlinear optical processes creates interesting possibilities for spin optoelectronics. In this Cheery paper, we attempt to explain in simple terms the concepts of optical and spin coherence, how the simultaneous occurrence of both types of coherence can be brought about by suitable arrangement of the magnetic field and polarization of exciting coherent light, and how the time development is governed by the nonlinear response of the system. We explain under what circumstances the single-particle effects dominate and under what circumstances the interaction effects between two excitons come to the fore. We relate to experiments by a theoretical formulation of how these effects are seen in a particular nonlinear optical experiment, namely the time-resolved Faraday relation spectroscopy. (C) 1998 Elsevier Science B.V. All rights reserved.