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

1895年，威廉·伦琴博士发现了x射线，这是上个世纪取得重大突破的重要一步。在医学上，这为医生提供了独特的诊断和治疗工具，对我们的社会产生了重大影响。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，都期望使用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。这一探索促使世界各地建造x射线自由电子激光器（XFEL）设施，提供高亮度的飞秒x射线激光脉冲。除了数十亿欧元的巨额财政投资外，这种设施的缺点是可用性有限，从而限制了可以进行的实验数量。****利用高谐波产生（HHG）过程，我们将开发一种台式高通量x射线激光器，用于在氧化物材料中进行高达氧k边（2.4 nm）的吸收测量。为了获得高通量的软x射线光子，将基于频域光参量放大（FOPA）的概念发展一种新的激光技术。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。在FOPA中使用高平均功率皮秒泵浦激光器，在2微米的20飞秒脉冲中，以10 kHz的重复率可获得高达50瓦的平均功率。这样的激光系统将为x射线材料表征铺平新的应用，也为紧凑加速器和明亮太赫兹光源的发展铺平了道路

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.**