双色场驱动不对称分子气体产生平台区超连续光谱

A supercontinuum in the plateau generated by asymmetric molecular gases exposed to a two-color field

研究了双色场驱动下不对称分子气体产生的高次谐波.通过计算机数值模拟,发现当波长为800nm,脉宽为10fs的基频场和波长为1200nm的控制场组成的多光周期双色场作用于不对称分子时,不对称分子的高次谐波在平台区的末端呈现出超连续结构.超连续谱谱宽达80eV,可以支持傅里叶极限脉宽为50as的脉冲输出.传播后,超连续谱变得更平滑,而且,直接选取超连续谱上的一段,可以得到脉宽约为90as的单个脉冲输出.

The high order harmonic generation （HHG） from asymmetric molecular gas in two-color field has been investigated and a method for broadband supercontinuum generation in the plateau by asymmetric molecular gas exposed to multicycle laser pulse is proposed. The numerical simulation shows that the harmonics at the end of the plateau become continuous and form a supercontinuum with a bandwidth of about 80 eV,from which a 50 as pulse in the transform limited case can be generated,when asymmetric molecules are exposed to a multicycle two-color field,which is synthesized by a 10 fs /800 nm fundamental pulse and a 15 fs /1200 nm control pulse. After propagation through the molecular gas,most of the modulations in the supercontinuum are eliminated,and the supercontinuum becomes smoother,from which a 90 as isolated pulse can be produced.