圆偏振周期量级红外激光脉冲驱动产生太赫兹辐射

Terahertz emission from air plasma produced by few-cycle circularly polarized laser pulses

摘要: 研究了周期量级的圆偏振激光在空气中成丝产生太赫兹辐射的偏振特性。将中心波长1.8 m、脉宽8.6 fs 的圆偏振红外激光脉冲聚焦到空气中，形成等离子体细丝，产生太赫兹辐射。通过测量太赫兹辐射的偏振状态，和偏振方向与驱动激光载波-包络相位的关系，发展太赫兹波偏振控制的方法。实验结果表明，太赫兹辐射为椭圆偏振，而且偏振平面随着驱动激光载波-包络相位的变化而转动。这对太赫兹波的偏振控制有重要意义，并为周期量级激光载波-包络相位的测量提供了新方法。

Abstract: The polarization characters of terahertz emission from air plasma produced by few cycle circularly polarized laser pulses were studied. Terahertz waves were generated from the air plasma produced by focusing the 8.6 fs circularly polarized laser pulses into the air. By measuring the polarization of terahertz waves and the relationship between the polarization and the carrier-envelope phase of driving laser, new methods for terahertz polarization control were developed. The terahertz emission was measured to be elliptically polarized, and its polarization rotated with the carrier-envelope phase of driving laser. This is useful for terahertz polarization control and provides a way to measure the carrier-envelope phase of few-cycle laser pulses in the air.