Extreme ultraviolet (XUV) frequency comb is a powerful tool in precision measurement. It also brings many new opportunities to the field of strong field physics since high harmonic generation related phenomena can be studied with high repetition rate. We demonstrate the generation of an XUV frequency comb with the aid of intra-cavity high harmonic generation process. The setup is driven by a high power infrared frequency comb, and an average power of 4.5 kW is reached in the femtosecond enhancement cavity. With Xe gas as the working media, harmonics up to the 19th order are observed. Power measurement indicates that as much as 115.9 μW (1.3 mW) are generated at ∼94 nm (∼148 nm). The shortest wavelength we can reach is ∼55 nm. The coherence of the generated light is tested with an optical-heterodyne-based measurement of the third harmonic. The resulted line width is ∼3 Hz. In addition, with this system, we also observe a strong suppression of below threshold harmonics from O₂ compared to that from Xe. These results suggest that the current system is ready for precision spectroscopic measurements with few-electron atomic and molecular systems in XUV region as well as the study of strong field physics with an unprecedented 100MHz repetition rate.

极紫外 (XUV) 频率梳是精密测量的强大工具。它还为强场物理领域带来了许多新的机会，因为可以以高重复率研究与高次谐波产生相关的现象。我们演示了借助腔内高次谐波生成过程生成 XUV 频率梳。该装置由高功率红外频率梳驱动，飞秒增强腔的平均功率达到 4.5 kW。以氙气作为工作介质，可以观察到高达 19 次的谐波。功率测量表明高达 115.9 μW（1.3 mW）在~94 nm（~148 nm）处产生。我们可以达到的最短波长是~55 nm。使用基于光学外差的三次谐波测量来测试生成光的相干性。结果线宽为~3 Hz。此外，通过该系统，我们还观察到与来自 Xe 的相比，来自 O _{2的低于阈值谐波的强烈抑制。}这些结果表明，当前系统已准备好在 XUV 区域使用少电子原子和分子系统进行精密光谱测量，以及以前所未有的 100MHz 重复频率研究强场物理。