中红外组合激光场调控宽带超连续谱的产生

本文对原子在波长为2000nm、脉宽为12.5fs的中红外驱动脉冲和脉宽为1.3fs的紫外控制脉冲叠加形成的组合场中产生的高次谐波进行了研究.通过组合场驱动氦原子得到了谱宽为230eV的超连续谱.利用组合场产生的谐波比单独利用中红外脉冲产生的谐波的强度高了3个量级.对超连续谱进行滤波并调节组合场中两束激光的延迟时间,可以直接产生100as的单个脉冲.我们发现超连续谱的宽度和位置几乎不会因为驱动场和控制场强度的变化而改变,这种性质有利于从实验上获得单个宽谱阿秒脉冲.

A broadband supercontinuum generated by helium atom exposed to combined mid-infrared laser field

By solving the one-dimensional time-dependent Schr?dinger equation with split-operator method, we study the high harmonics generated by helium atom, and analyse the characteristics of the attosecond pulses generated by the high-order harmonics. By adopting a mid-infrared driving pulse (with wavelength of 2000 nm and pulse duration of 12.5 fs) combined with a short UV controlling pulse, a smooth supercontinuum with the bandwidth of 230 eV is observed. By adjusting the delay between the mid-infrared and ultraviolet fields, the contribution of the short quantum trajectory can be efficiently enhanced and an isolated 100 as pulse seems achievable. We found that the supercontinuum is not sensitive to the intensities of the two lasers, which facilitates the experimental implementation for the isolated attosecond pulse generation.