One-photon and two-photon spectroscopy and spin polarization

On the basis of a higher-band Kane model for the energy-band structure and a multi-order perturbation theory of the spin-polarized electronic transport model a theoretical investigation has been carried out for the optically generation of spins via both one-photon and two-photon spectroscopy in materials with a zinc-blende structure (zinc-blende semiconductors). As the optically excited hole spin relaxation is extremely fast, the calculation for the polarization gives effectively the electronic spin polarization. It is found that the electron spin polarization depends on the mode of the spectroscopy and the excitation photon energy. On comparison between two spectroscopic modes, it is clear that the multiphoton spectroscopy enhances ~ 10% of the electron spin polarization. The reason for the possibility of enhancing the effect is discussed