在用超短激光脉冲产生和测量阿秒脉冲的过程中,绝对相位成为一个非常重要的影响因素。讨论了绝对相位对阿秒脉冲的产生和激光振荡的关系的影响,发现高次谐波的产生过程非常稳定,阿秒脉冲和驱动它的激光振荡之间的稳定的相位关系并不会受绝对相位的随机性的破坏,从而为采用交叉相关技术直接测量由强场原子高次谐波过程产生的阿秒脉冲宽度提供了理论依据,正确解释了文献［13］上报道的实验结果。

In the generation and measurement of attosecond pulse using a few cycle laser pulse, the absolute phase of the laser pulse has been an important factor. The relation between the generation of attosecond pulse and the laser oscillation and how the absolute phase affects this relation are discussed. According to our calculation, the random of the absolute phase will not destroy the stability between the attosecond pulse and the laser oscillation. This result supports the direct measurement of the duration of the attosecond pulse with cross-correlation technique theoretically and gives an exact explanation for the experiment result in Ref.