激光脉宽对谐波频移和振幅强度的影响

数值研究了激光脉宽对H_2~+和T_2~+谐波辐射的影响.计算结果表明:(i)对于谐波频移现象:在少周期激光场下,H_2~+和T_2~+谐波辐射呈现红移.随着激光脉宽增大,H_2~+谐波辐射呈现蓝移; T_2~+谐波辐射红移减弱.(ii)对于谐波振幅强度:H_2~+和T_2~+谐波辐射强度会随着激光脉宽增大而增强.但是,在少周期激光场下,H_2~+谐波截至能量附近的强度要大于T_2~+.在多周期激光场下,T_2~+谐波截至能量附近的强度要大于H_2~+.

Pulse duration effect on frequency and amplitude modulation of harmonics

Laser pulse duration effect on the high-order harmonic generation from H2+ and T2+ has been theoretically investigated. The results show that (i) in the aspect of the frequency modulation of harmonics, the red-shifts of the harmonics from H2+ and T2+ can be found in the few-cycle pulse. As the pulse duration increases, the harmonics from H2+ present the blue-shifts and the red-shifts of the harmonics from T2+ are decreased. (ii) In the aspect of the amplitude modulation of harmonics, the intensities of the harmonics from H2+ and T2+ can be enhanced as the pulse duration increases. However, for the case of the few-cycle pulse, the intensities of the harmonic cutoffs from H2+ are higher than those from T2+. For the case of the multi-cycle pulse, the intensities of the harmonic cutoffs from T2+ are higher than those from H2+.