中文摘要：

采用多周期800nm激光组合1600nm红外激光脉冲辐照氦离子He＋叠加态生成强、短孤立阿秒脉冲.结果表明,相对于800nm单色激光辐照基态情形,截止频率由70次谐波大幅度展宽到280次谐波,且获得频宽为108eV并由单一短量子路径贡献的连续辐射谱,叠加该连续谱210次到280次谐波获得了脉宽为38as的强、短孤立脉冲,其强度比单色场情形提高了11个数量级.研究进一步表明,两束激光脉冲的时间延迟从0.05π到-0.05π之间获得的孤立阿秒脉冲是最优化的,且脉冲持续时间均为38as,这使得该方案在实验上具有可操作性.

英文摘要：

A scheme to efficiently generate an intense short isolated attosecond pulse is presented by the combined laser pulse irradiating the coherent superposition state.The combined pulse is composed of a multi-cycle 800 nm laser and a 1600 nm one.Compared with the case of the fundamental laser irradiating the ground state,the cutoff position is significantly extended from 70th to 280th harmonic,a broadband supercontinuum spectrum with 108 eV spectral width can be produced which directly generates an isolated 38 attosecond pulse,the intensity of which is increased eleven orders of magnitude.Our simulation also shows that the value of the time delay has a large range to keep the isolated sub-50-as pulse generation.Moreover,the value of the time delay in the range between ± 0.05π is optinal.This result shows that the scheme appears feasible for an experimental demonstration.