论文标题
红外单周脉冲在高阶谐波中引起的高能高原
Infrared single-cycle pulse induced high-energy plateaus in high-order harmonic spectroscopy
论文作者
论文摘要
由新兴实验的动机[例如\ textit {z。 Nie等。纳特。光子。 \textbf{12}, 489 (2018)}] on producing infrared (IR) single cycle pulses in the spectral region 5 - 14 $μm$, we theoretically investigate their role for controlling high-order harmonic generation (HHG) process induced by an intense near-infrared (NIR) multi-cycle pulse ($λ$ = 1.27 $μm$).通过时间依赖性schrödinger方程的数值模拟，证明了该方案为氢原子的原型。特别是，我们表明，组合的脉冲允许一个人产生均衡的谐波，最重要的是产生高能量的高原，并且与单独使用NIR脉冲相比，谐波截止量增加了3倍。出现的高能量高原被理解，这是由于在NIR场旅行时从单个周期磁场转移到电离电子的巨大动量转移，因此导致了高弹药电子的回忆。我们还确定了IR单周场通过IR场诱导的电子位移效应来控制发射电子的方向性的作用。我们进一步表明，可以通过改变两种脉冲之间的相对载体 - 内玻璃相和波长之间的相对载体 - 内玻璃相控制。因此，我们的发现开辟了使用IR单周辅助高谐波光谱法的时间分辨电子衍射的新观点。
Motivated by the emerging experiments [e.g. \textit{Z. Nie et al. Nat. Photon. \textbf{12}, 489 (2018)}] on producing infrared (IR) single cycle pulses in the spectral region 5 - 14 $μm$, we theoretically investigate their role for controlling high-order harmonic generation (HHG) process induced by an intense near-infrared (NIR) multi-cycle pulse ($λ$ = 1.27 $μm$). The scenario is demonstrated for a prototype of the hydrogen atom by numerical simulations of the time-dependent Schrödinger equation. In particular, we show that the combined pulses allow one to generate even-order harmonics and most importantly to produce high-energy plateaus and that the harmonic cutoff is extended by a factor of 3 compared to the case with the NIR pulse alone. The emerged high-energy plateaus is understood as a result of a vast momentum transfer from the single-cycle field to the ionized electrons while travelling in the NIR field, and thus leading to high-momentum electron recollisions. We also identify the role of the IR single-cycle field for controlling the directionality of the emitted electrons via the IR-field induced electron displacement effect. We further show that the emerged plateaus can be controlled by varying the relative carrier-envelope phase between the two pulses as well as their wavelengths. Thus, our findings open up new perspectives for time-resolved electron diffraction using an IR single-cycle field-assisted high-harmonic spectroscopy.
