中文摘要：

提出了利用空气成丝产生的太赫兹波测量少数周期激光的初始载波包络相位（CEP）的方法。空气等离子体产生的太赫兹波形的演变可以用来探测传播中的少数周期激光的载波包络相位的变化。在少数周期强激光场，太赫兹波形反转的数目和反转位置都有规律地依赖于少数周期激光的载波包络相位。利用光电流模型的计算结果表明，在适中的能量范围内，对于所有的初始CEP，太赫兹波形反转点数目是两个或者一个，且在不同输入能量下，总是在初始CEP为0.5π时，太赫兹波形的两个反转点变为一个反转点。这可以提供准确测量驱动激光场初始CEP的方法。

英文摘要：

Using the THz emission from air plasma, the method of determining the initial carrier-envelope phase （CEP） of few-cycle pulses was proposed. In air plasma, the evolution of the generated THz waveform can be used to probe the variation of the CEP of propagating intense few-cycle pulses. In the intense few-cycle laser fields, the inversions position and the number of inversions of the THz waveforms was found dependent on the initial CEP regularly. The calculation based on the transient photocurrent model indicates that the number of inversions of the THz waveforms is either two or one for all the initial CEP for a range of moderate input pulses energies. Under varied input pulse energies, the value of initial CEP is 0.5π constantly when the two inversions of the THz waveforms change to one. This provides a method of measuring the initial CEP of the driving few-cycle pulses.