Hrisafov S, Pupeikis J, Chevreuil P-A, Brunner F, Phillips C R, Gallmann L, Keller U
Opt Express. 2020 Dec 21;28(26):40145-40154. doi: 10.1364/OE.412564.
We present a near-infrared optical parametric chirped-pulse amplifier (OPCPA) and soft X-ray (SXR) high-harmonic generation system. The OPCPA produces few-cycle pulses at a center wavelength of 800 nm and operates at a high repetition rate of 100 kHz. It is seeded by fully programmable amplitude and phase controlled ultra-broadband pulses from a Ti:sapphire oscillator. The output from the OPCPA system was compressed to near-transform-limited 9.3-fs pulses. Fully characterized pulse compression was recorded for an average power of 22.5 W, demonstrating pulses with a peak power greater than 21 GW. Without full temporal characterization, high-power operation was achieved up to 35 W. We demonstrate that at such high repetition rates, spatiotemporally flattened pump pulses can be achieved through a cascaded second-harmonic generation approach with an efficiency of more than 70%. This combination provides a compelling OPCPA architecture for scaling the peak power of high-repetition-rate ultra-broadband systems in the near-infrared. The output of this 800-nm OPCPA system was used to generate SXR radiation reaching 190 eV photon energy through high-harmonic generation in helium.
我们展示了一种近红外光学参量啁啾脉冲放大器（OPCPA）和软X射线（SXR）高次谐波产生系统。该OPCPA在中心波长800nm处产生少周期脉冲，工作重复频率为100kHz。它由来自钛宝石振荡器的完全可编程幅度和相位控制的超宽带脉冲作为种子源。OPCPA系统的输出被压缩至近变换极限的9.3飞秒脉冲。记录了平均功率为22.5W时的完全表征的脉冲压缩情况，展示了峰值功率大于21GW的脉冲。在未进行完全时间表征的情况下，实现了高达35W的高功率运行。我们证明，在如此高的重复频率下，通过级联二次谐波产生方法可以实现时空平坦的泵浦脉冲，效率超过70%。这种组合为扩大近红外高重复频率超宽带系统的峰值功率提供了一种引人注目的OPCPA架构。该800nm OPCPA系统的输出用于通过在氦气中进行高次谐波产生来产生达到190eV光子能量的SXR辐射。
