Optical conductivity of a two-dimensional electron gas with Rashba and Dresselhaus spin-orbit coupling.

We investigate the optical conductivity and plasmon spectrum of a two-dimensional electron gas with Rashba and Dresselhaus spin-orbit interaction. Using the self-consistent field approach we derive expressions for the dispersion relations of the intra- and inter-SO plasmons. We found that the latter are immersed within the continuum of inter-SO single-particle excitations. The intra-SO plasmons remain undamped and almost unaffected by the spin-orbit coupling. Remarkably, the optical conductivity shows however a dependence on the direction of the externally applied electric field, caused by the anisotropic splitting of the spin states. In addition to the control through the driving frequency or electrical gating, this new aspect of the optical absorption spectrum might be useful in spintronics applications.