不同啁啾调制对光谱连续区的影响

Effects of different chirps on spectral continuum

摘要:

利用啁啾场调控激光波形，理论研究了不同啁啾场对高次谐波光谱的影响. 结果表明：当采用对称中间啁啾调控时，谐波截止能量的延伸及光谱连续区来自于激光中间区域. 当采用不对称负向啁啾调控时，谐波截止能量的延伸及光谱连续区来自于激光下降区域. 虽然，谐波截止能量在不同啁啾调控下都可以得到延伸，但是，不对称负向啁啾场下光谱连续区的强度要比对称中间啁啾场下光谱连续区强度高2个数量级. 最后，通过叠加光谱连续区上的谐波可以获得2个脉宽在38 as的单个阿秒脉冲. 并且，负向啁啾场下获得脉冲强度要比对称中间啁啾场下获得脉冲强度高2个数量级.

Abstract:

The effects of high-order harmonic generation on different chirps have been investigated using the laser waveform control modulated by chirped pulse. The results show that when using the symmetric-mid-chirped pulse, the extension of harmonic cutoff and spectral continuum come from the middle part of the laser field. However, when using the asymmetric-down-chirped pulse, the extension of harmonic cutoff and spectral continuum stem from the falling part of the laser field. Although the harmonic cutoffs from different chirped pulses can be extended, the intensity of spectral continuum from asymmetric-down-chirped pulse is two orders of magnitude higher than that from the symmetric-mid-chirped pulse. With the superposition of harmonics on the spectral continuum, two single attosecond pulses with a pulse width of 38 as can be obtained. Moreover, the intensity of attosecond pulse obtained from the asymmetric-down-chirped pulse is two orders of magnitude higher than that from the symmetric-mid-chirped pulse.