CAJ | 학술논문

通过数值求解一维含时薛定谔方程,本文研究了具有特定波长的双色激光脉冲与氦原子相互作用产生的高次谐波和阿秒脉冲,这里双色激光脉冲由5 fs较低强度基频钛宝石主脉冲与另一束较高强度的1330 nm红外附加脉冲构成.研究发现,若两束脉冲之间的相对相位选择合适,可以获得宽带连续辐射的高次谐波谱,叠加该连续辐射谱可获得脉宽为38 as的孤立短脉冲.进一步研究发现,不同于以往孤立阿秒脉冲研究中选出长、短量子路径之一作为辐射源,这里单阿秒脉冲来源于长、短两个量子路径的贡献,只是这两个量子路径在很宽的谐波次数变化范围内辐射时刻比较集中.
통과수치구해일유함시설정악방정,본문연구료구유특정파장적쌍색격광맥충여양원자상호작용산생적고차해파화아초맥충,저리쌍색격광맥충유5 fs교저강도기빈태보석주맥충여령일속교고강도적1330 nm홍외부가맥충구성.연구발현,약량속맥충지간적상대상위선택합괄,가이획득관대련속복사적고차해파보,첩가해련속복사보가획득맥관위38 as적고립단맥충.진일보연구발현,불동우이왕고립아초맥충연구중선출장、단양자로경지일작위복사원,저리단아초맥충래원우장、단량개양자로경적공헌,지시저량개양자로경재흔관적해파차수변화범위내복사시각비교집중.
We have investigated theoretically the high-order harmonics and attosecond pulse generation by numerically solving the one-dimensional time-dependent Schr¨odinger equation from a helium atom in a two-color laser field, which is synthesized by adding a 1330-nm infrared pulse with higher intensity to an 800-nm fundamental pulse with lower intensity. Our results clearly show that if the phase difference between the two pulses is selected suitably, the generation of high-order harmonics spectrum with a broadband supercontinuum characteristic can be achieved, and an isolated 38 as pulse can be realized. By the time-frequency analysis, we find that the isolated attosecond pulse comes from the contribution of the long and short quantum paths, and for these two quantum paths the change of emission time with the harmonics order is rather slow. This is different from the traditional isolated attosecond pulse generation that a single quantum path needs to be picked up to obtain an isolated attosecond pulse.