Femtosecond laser amplifier with optic parametric amplifier

采用参数化光放大器的飞秒激光放大系统，实现超短极紫外光脉冲的时间分辨光电子能谱实验。该激光系统将特别用于泵浦两个高谐波产生光源，用于与光学参数放大器结合产生XUV光，该光源将用作可见光范围内的可调谐光源，用于定制样品的激发。利用角分辨光电子能谱仪和所谓的动量显微镜，我们将在准绝热（热电子的弛豫动力学）和非绝热（强激发后的多体弛豫动力学，光诱导相变）下进行实验。将涉及以下研究领域：1)混合界面的超快动力学；2)相关材料的相分离；3)相关材料的能带结构动力学；4)低维系统的电子动力学；5)超快退磁中的自旋相关瞬态能带结构；6)混合界面的飞秒轨道层析成像；7)钙钛矿卤化物的光激发飞秒放大器系统将补充现有的激光系统。这是由于上述项目和另外5个项目在光谱学领域完全超负荷。现有的激光器将仅用于光谱学实验，而新的激光系统将用于光电子能谱学实验。

The Femtosecond-Laser-Amplifier System with Parametric Optical Amplifier will be used to realise time-resolved photoelectron spectroscopy experiments with ultrashort extreme ultraviolet (XUV) light pulses. The laser system will in particular be used to pump two high-harmonic generation light sources for the generation of XUV light in combination with an optical parametric amplifier, which will be used as a tuneable light source in the visible range for a tailored excitation of the samples. Using both an angle-resolved photoelectron spectrometer and a so-called momentum microscope, we will carry out experiments in a quasi-adiabatic (relaxation dynamics of hot electrons) and in a non-adiabatic regime (many-body relaxation dynamics after a strong excitation, optically induced phase transitions). The following fields of research will be covered:1) Ultrafast dynamics at hybrid interfaces2) Phase separation in correlated materials3) Band-structure dynamics in correlated materials4) Electron dynamics in low-dimensional systems5) Spin-dependent transient band structures in ultrafast demagnetisation6) Femtosecond orbital tomography at hybrid interfaces7) Photoexcitations in perovskite halidesThe femtosecond amplifier system will supplement an already available laser system, which is due to the above-mentioned projects and additional 5 projects in the area of optical spectroscopy completely overloaded. The already available laser will then be used for the optical spectroscopy experiments, only, and the new laser system will be used for the photoelectron spectroscopy experiments.