Optical injection processes in semiconductors

We present a theoretical review and band structure calculations of optical injection processes in semiconductors. The study of these processes in bulk materials provides a benchmark and reference for their future applications in quantum wells and other nanostructures. We discuss the injection and coherent control of charge, spin, current, and spin current in bulk GaAs using a full-Brillouin zone, 30-band k·p model in the independent-particle approximation. Carrier injection and optical orientation are presented for one- and two-photon absorption, including anisotropy and linear-circular dichroism in the two-photon absorption coefficients. Quantum-mechanical interference effects are considered in carrier, spin, current, and spin current excitation using coherent optical field components at frequencies ω and 2ω. We calculate the spectral dependence of these all-optical effects for excitation energy in the range from 0 eV to 4 eV. Significant spin and spin current injection is found for transitions away from the Brillouin-zone center at the E1 resonance.