空气飞秒激光成丝现象中产生的椭圆偏振单周期太赫兹脉冲

Elliptical Polarized Single-Cycle THz Pulse Generated by Femtosecond Laser Filamentation in Air

飞秒激光在空气中形成的等离子体细丝会辐射出太赫兹(THz)信号。实验利用1 mJ,800 nm,50 fs的飞秒激光脉冲产生等离子体细丝。应用光电取样方法探测了激光成丝现象中前向辐射的THz脉冲,得到了持续时间为0.1 ps、光谱峰值在1 THz左右的单周期THz脉冲。转动抽运光的偏振态,分析了电光取样信号的变化。通过比较实验数据和计算结果,证明了成丝辐射THz脉冲的偏振态为椭圆偏振态。

Strong forward propagated THz pulse can be generated by femtosecond laser filamentation in air. An electro-optical sampling based time domain spectroscopy （TDS） technique is used to diagnose the THz pulse produced by a femtosecond laser filament in air. The filament is generated by a 1 mJ, 50 fs laser pulse centered at 800 nm. The THz pulse measured in experiment is a single-cycle pulse （pulse width is lps） and the corresponding spectrum peak value is around 1 THz. The polarization orieatation of pump beam is rotated and the variation of electro-optical sampling signal is analyzed-Compared the experimental results with the calculational results, the polarization of THz pulse emitted from filamentation is elliptical.