阿秒电离门调控宽带超连续谱的传播特性

Propagation characteristics of the broadband supercontinuum with an attosecond ionization gate

通过数值模拟三维传播方程研究了双色场阿秒电离门技术调控产生高次谐波的传播特性.发现波长800和400nm的5fs双色场电离门调控产生的谐波在传播0.5mm后由于短轨道满足相位匹配条件,实现了短轨道的选择,在平台区得到了高效率、无调制的宽带超连续谱(谱宽达80eV).模拟不同传播距离的结果表明该连续谱能够在介质中稳定存在.对该连续谱中60—90eV的谐波直接进行滤波可以得到高效率、脉冲宽度约为135as的单脉冲.这种性质对实验上实现利用阿秒电离门调控产生高效率宽谱单阿秒非常有利.

The propagation of high-order harmonics with attosecond ionization gate is simulated with three-dimensional propagation equation. After 0.5 mm propagation distance, the short trajectories in the harmonics, which are generated by two 5 fs laser pulses centered at 800 and 400 nm, are selected and a highly efficient smooth supercontinuum with the bandwidth of about 80 eV is obtained in the plateau, because of the phase matching. Simulation results of different propagation distances show the broadband supercontinuum can last steadily. A highly efficient pure isolated attosecond pulse with the duration of about 135 as can be generated by directly filtering out of the harmonics from 60-90 eV in the supercontinuum, and a single 50 as pulse can be generated, which facilitates the experimental implementation for the isolated attosecond pulse generation.