Generation of highly spin-polarized electron beams by using two-photon excitation process from GaAs semiconductors.

当激光功率在GaAs半导体双光子激发的阈值功率附近时，测得的电子自旋极化率（ESP）仅为20%左右，远低于估计值（大于90%）。分析认为，ESP退化是由于激发激光中谐波的存在和GaAs半导体中杂质能态的存在引起的。为了获得90%以上的电除尘器，我们必须对激光系统和样品制备进行更复杂的研究和开发。

In case that the laser power was around the threshold power of two photon excitation from GaAs semiconductors, it is found that the measured electron spin polarization (ESP) was only around 20%, which is much lower than estimated value, which is higher than 90%. It is considered that the ESP degradation is caused by the exists of harmonics in excitation laser and impurity energy states in GaAs semiconductors. To obtain higher than 90% ESP, we have to make more complicate researches & developments for laser system and sample preparation.