High harmonic sources can provide ultrashort pulses of coherent radiation in the XUV and X-ray spectral region. In this paper we utilize a sub-two-cycle femtosecond fiber laser to efficiently generate a broadband continuum of high-order harmonics between 70 eV and 120 eV. The average power delivered by this source ranges from > 0.2 µW/eV at 80 eV to >0.03 µW/eV at 120 eV. At 92 eV (13.5 nm wavelength), we measured a coherent record-high average power of 0.1 µW/eV, which corresponds to 7 · 10⁹ ph/s/eV, with a long-term stability of 0.8% rms deviation over a 20 min time period. The presented approach is average power scalable and promises up to 10¹¹ ph/s/eV in the near future. With additional carrier-envelop phase control even isolated attosecond pulses can be expected from such sources. The combination of high flux, high photon energy and ultrashort (sub-) fs duration will enable photon-hungry time-resolved and multidimensional studies.

中文翻译：

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亚二周期光纤激光器在XUV中产生相干宽带高光子通量连续谱

高谐波源可以在XUV和X射线光谱区域中提供相干辐射的超短脉冲。在本文中，我们利用亚二周期飞秒光纤激光器有效地产生了70 eV至120 eV之间的高次谐波宽带连续体。该电源提供的平均功率范围在80 eV时> 0.2 µW / eV至120 eV时> 0.03 µW / eV。在92 eV（13.5 nm波长）下，我们测得的相干记录高平均功率为0.1 µW / eV，相当于7·10 ⁹ ph / s / eV，长期稳定性在a范围内为0.8％rms偏差。 20分钟的时间段。提出的方法是平均功率可扩展的，并承诺最高10 ¹¹ph / s / eV在不久的将来。借助附加的载波包络相位控制，甚至可以从此类源获得隔离的阿秒脉冲。高通量，高光子能量和超短（亚）fs持续时间的结合将使光子饥饿的时间分辨和多维研究成为可能。