瞬态光学研究室知识库

The influence of the polarization angle between two;color lasers on the Terahertz (THz) emission was investigated based on a modified two;dimensional transient current model. By changing the polarization angle between the fundamental frequency laser and its second harmonic laser beam, it is found that, the emitted THz amplitude varys periodically with the chaning of the polarization angle in laser plasma, and the optimal angle is also changed with the different laser intensity. Under the comparatively low laser intensity (≤2×1014W/cm2), the THz amplitude can reach the maximum when the two;color lasers have the same polarization. However, the optimal angle will increase with the increasing of the total laser intensity when the laser intensity is high enough(>2×1014W/cm2). The electron density was firstly used to analyze this phenomenon under comparatively low laser intensity and then the residual drift current was utilized to reveal the underlying physical mechanism. It was found that, the residual current density is the essential source of the THz waves and which can determine the intensity of THz emission © 2016, Science Press. All right reserved.