Optical orientation in quantum wells

In this paper, we review the optical selection rules in semiconductor quantum wells and discuss the degree of electron spin polarization in dependence of the excitation energy and the optical excitation direction. We describe the very fast initial spin relaxation at large excess energies in very thin quantum wells and quantify the dependence on excitation density. As examples for optical studies and the rich spin dynamics in quantum wells, we present the electron spin dynamics in (110)-oriented GaAs quantum wells unveiling the intersubband spin relaxation mechanism and experiments on the complex spin dynamics of coupled electron–hole spins.