Table-top soft X-ray absorption spectroscopy based on high average/peak power femtosecond laser

威廉·伦琴博士在1895年发现X射线，是上个世纪科学取得重大突破的重要一步。在医学方面，这对我们的社会产生了重大影响，为医生提供了独特的诊断和治疗工具。在科学研究中，X射线用于原子、分子、生物结构和材料的光谱和结构表征。今天，来自不同科学领域的研究人员，包括生物学家，化学家和物理学家，都在期待使用X射线激光脉冲来探测具有高空间和高时间分辨率的动态过程。这种探索激发了世界各地X射线自由电子激光（XFEL）设施的建设，提供高亮度的飞秒X射线激光脉冲。这种设备的缺点是，除了其数十亿欧元的巨额财政投资之外，它的可用性有限，从而限制了可以进行的实验数量。使用高次谐波产生（HHG）过程，我们将开发一台台式高通量X射线激光器，用于测量氧化物材料中氧气k边（2.4 nm）的吸收。为了获得高通量的软X射线光子，将基于频域光学参量放大（FOPA）的概念开发一种新的激光技术。这项由INRS研究人员开发的颠覆性技术能够有效放大中红外光谱范围内的超短脉冲。使用高平均功率皮秒泵浦激光器的FOPA，高达50 W的平均功率将可在20飞秒脉冲在2微米，重复率为10 kHz。这样的激光系统将为X射线材料表征铺平新的应用，同时也为紧凑型加速器和明亮的THz源的开发铺平新的应用。

The discovery of X-rays in 1895 by Dr. William Roentgen has been an important step towards major breakthroughs in the last century. In medicine, this has had a major impact on our society by providing physicians with unique tools for diagnostics and treatments. In scientific research, X-rays are used for spectroscopic and structural characterization of atoms, molecules, biological structures and materials. Today, researchers from a broad diversity of scientific horizons, including biologists, chemists and physicists, are anticipating using X-ray laser pulses to probe dynamical processes with combined high spatial and high temporal resolutions. This quest motivates the construction of X-ray Free Electron Laser (XFEL) facilities around the world providing femtosecond X-ray laser pulses of high brilliance. The drawback of such facility, on top of its huge financial investment of billions of Euros, is its limited availability thus restraining the number of experiments that can be performed.Using the process of high harmonic generation (HHG), we will develop a table-top high flux X-ray laser to perform absorption measurements up to the Oxygen k-edge (2.4 nm) in oxide materials. To reach a high flux of soft X-ray photons, a new laser technology will be developed based on the concept of Frequency domain Optical Parametric Amplification - FOPA. This disruptive technology, developed by the INRS researchers, enables the efficient amplification of ultrashort pulses in the mid-infrared spectral range. Using a high average power picosecond pump laser for the FOPA, up to 50 W of average power will be available within 20 femtosecond pulses at 2 microns at a repetition rate of 10 kHz. Such a laser system will pave new applications for material characterization with X-rays, but also for the development of compact accelerators and bright THz sources.