中文摘要：

数值计算了线偏振的超短激光脉冲（脉冲持续时间为两个光学周期）与一维模型原子相互作用产生的高次谐波发射功率谱.研究表明,当载波相位发生变化时,超短脉冲谐波谱的截止频率也随之改变,而且在特定相位下,谐波谱出现了明显的双平台结构.对此,采用半经典的＂三步＂模型给出了合理解释,并利用小波时频分析方法证实＂三步＂模型可以准确预言超短脉冲谐波谱的截止频率.

英文摘要：

We numerically calculated the high-order harmonic generation （HHG） power spectra from a one-dimensional model atom irradiated by linearly polarized ultra-short laser pulses whose duration is two optical cycles. It was found that, the cut-off positions of the HHG spectra change when the carrier phases of the ultra-short laser pulses are altered, and the distinct double plateau structure appears in some special carrier phases. The above issues are reasonably explaned by the three-step model. Finally, the wavelet time-frequency analysis verifies that the three-step model can accurately exactly predict the cut-off frequencies of the ultra-short pulse HHG spectra.