少周期飞秒准径向偏振光的超快瞬变聚焦矢量场

研究了基于腔外螺旋相位调制获取高峰值功率飞秒准径向偏振光的方法,结果表明该方法所产生的并非完全纯净的径向偏振光,其径向分量决定了聚焦后纵场的分布,而径向和角向分量共同影响了横场的分布.根据Richard-Wolf矢量衍射理论模拟得到不同纯度下的少周期飞秒准径向偏振光在焦点附近的电场的时空矢量分布,发现其具有中心对称和震荡衰减特点,载波包络相位将对聚焦场的矢量时空分布产生显著影响,从而对飞秒脉冲与电子在聚焦场中的相互作用产生影响.研究结果可为进一步的激光粒子加速分析以及偏振转换器的设计提供依据.

Ultrafast Transient Focal Vector Field of Few-cycle Femtosecond Quasi Radially Polarized Beams

The extra-cavity quasi-continue spiral phase modulation method for generating high peak power quasi-radially polarized beam was studied,which show that the generated beam is not perfect radially polarized,the radially polarized components determine the longitudinal electric field distribution,and the transversal field distribution is determined by both of the radially and the azimuthally polarized components.Considering the Richard-Wolf vector diffraction theory,the spatial and temporal distribution of the electric field vectors around the focal spot for various purities were simulated.The results show that the spatial and temporal distribution possesses the features of centrosymmetry and oscillation attenuation,and will be remarkably affected by the carrier envelope phase.Furthermore,the analysis indicates that the interactions between the focused pulse and the electron will be significantly determined by the spatial and temporalvector distribution at the focal spot.The results will provide valuable basis for the laser-particler interaction analysis and further polarization convertor designs.