附加谐波脉冲生成强的39阿秒孤立脉冲

采用多周期800 nm激光组合它的27次谐波脉冲生成超短、宽频的孤立阿秒脉冲.研究表明,脉宽为1 fs的27次谐波脉冲可以有效地控制电子动力学过程.将其加入到单色激光场的特定时域,可以控制电离概率在半个光学周期内迅速提升,使得谐波的转化效率相对于单色场情形增强4个数量级,并实现单一的短量子路径选择,出现频宽为108 eV的超连续辐射谱,叠加该连续谱140次到210次谐波获得了脉宽为39as的强、短孤立脉冲.与文献7]中采用5 fs/800 nm激光附加紫外阿秒脉冲的方法相比,该方案生成的连续谱频带增宽一 关键词： 组合激光脉冲 连续辐射谱 阿秒脉冲

Isolated intense 39 attosecond pulse generated by adding a harmonic pulse

A scheme to efficiently generate a broadband short attosecond pulse is presented by using intense multi-cycle 800 nm laser in combination with its 27th harmonic (H27) laser pulse. It is shown that the electronic dynamics can be efficiently controlled by the 1 fs H27 laser. Setting the H27 laser to the multi-cycle 800 nm laser at a proper time, we can control most of the ionizations to occur at half the optical cycle, and the short quantum path can be picked out, thus the harmonic plateau is heightened four orders of magnitude compared with the case of using the fundamental laser alone. Furthermore, a harmonic supercontinuum spectrum with a bandwidth of 108 eV is produced. By superposing the 140th-210th harmonics in the continuous region, an intense isolated pulse with the duration of 39 as is straightforwardly obtained. Using this method, the bandwidth of the continuum spectrum is 2 times wider, the intensity of the attosecond pulse is greater, and the duration of the attosecond pulse is shorter, in contrast to the scheme proposed in Ref. 7], which added the ultraviolet attosecond pulse to a few-cycle 800 nm laser.