静电场对高次谐波时频特性的影响  

The effects of static electric field on the time-frequency characteristics of high-order harmonic generation

作　　者：洪伟毅[1] 曹伟[1] 兰鹏飞[1] 陆培祥[1] 

机构地区：[1]华中科技大学武汉光电国家实验室,武汉430074

出　　处：《物理学报》2007年第11期6623-6628,共6页Acta Physica Sinica

基　　金：教育部博士点基金(批准号:20040487023);国家自然科学基金(批准号:10574050)资助的课题.~~

摘　　要：通过数值求解含时薛定谔方程,发现在静电场的作用下,对原子高次谐波谱截止区附近的谐波进行叠加可以得到脉冲间隔为一个光周期的阿秒脉冲链.利用这种性质,用12fs波长为800nm的激光附加强度为激光强度0.25%的静电场脉冲驱动He原子可以得到脉宽为220as的单个脉冲.当静电场与激光场幅度之比达到0.39时,原子谐波谱的截止区可以被拓宽到Ip+9.1Up,同时,次数高于Ip+0.7Up的谐波的相位几乎是锁定的,因此可以得到谱宽大于40eV且相位锁定的谐波.对这部分谐波进行叠加就可以得到脉宽小于100as的阿秒脉冲链.　The time-frequency properties of the high-order harmonic generation in the presence of a static electric field are investigated.It is found that an attosecond pulse train with one burst per optical cycle can be extracted by superposing the harmonics near the cutoff.This characteristic can be used to generate isolated attosecond pulse in multi-cycle regime.When the ratio of the laser field to the static field is 0.39,the harmonic spectrum is extended to Ip＋9.1Up,and the harmonics above Ip＋0.7Up are emitted almost in phase.The phase-locked harmonics covering a broad bandwidth are produced,and then a regular attosecond pulse train with the pulse duration less than 100 as is generated.

关 键 词：高次谐波 静电场 时频特性 

分 类 号：O437[机械工程—光学工程]