通过梯形激光场和半周期场的合成扩展高次谐波截止频率

本文提出了一个在少周期梯形激光场上叠加半周期场来扩展高次谐波谱截止频率的方案。通过采用求解含时薛定谔方程，理论模拟了一维模型氢分子离子体系在不同激光场条件下的高次谐波谱，并结合时频分布图，分析了半周期场对高次谐波产生的影响。计算结果表明，使用梯形激光和半周期场的组合方法，可以有效实现扩展谐波截止频率的目的。

Extension of high-order harmonic cutoff frequency via synthesizing a few-cycle trapezoidal laser field and a half-cycle field

In this paper, we present a method to extend the high-order harmonic cutoff frequency by synthesizing a few-cycle trapezoidal laser field and a half-cycle field. The high-order harmonic spectra in different intense laser fields can be obtained by numerically solving the non-Born-Oppenheimer approximation time-dependent Schrödinger equation. At the same time, the effect of half-cycle field on high-order harmonic generation is analyzed reasonably by using of the time-frequency distribution. The numerical results show that the harmonic cutoff frequency can be efficiently extended by using the way of combination of a few-cycle trapezoidal laser field and a half-cycle field.