Generation of XUV spectral continua from relativistic plasma mirrors driven in the near-single-cycle limit

Mirrorless focusing of XUV high-order harmonics

By experimentally studying high-order harmonic beams generated in gases, we show how the spatial characteristics of these ultrashort XUV beams can be finely controlled under standard generation conditions. For the first time, we demonstrate that these XUV beams can be emitted as converging beams and get thereby focused after generation. We study this mirrorless focusing using a spatially chirped beam that acts as a spatially localized probe located inside the harmonic generation medium. We analyze the XUV beam evolution with an analytical model providing the beam characteristics and obtain ver…

自调制等离子体镜的异常相对论辐射

Anomalous Relativistic Emission from Self-Modulated Plasma Mirrors

研究揭示了等离子体镜反射高阶谐波时，时空相干性丧失导致异常方向性辐射的高效产生机制，通过分析与粒子-细胞模拟验证了激光驱动的相对论电子微束振荡作用。

An easy technique for focus characterization and optimization of XUV and soft x-ray pulses

For many applications of extreme ultraviolet (XUV) and x-ray pulses a small focus size is crucial to reach the required intensity or spatial resolution. In this article, we present a simple way to characterize an XUV focus with a resolution of 1.85 micrometer. Furthermore, this technique is applied for the measurement and optimization of the focus of an ellipsoidal mirror for photon energies ranging from 18 to 150 eV generated by high-order harmonics. We envisage a broad range of applications of this approach with sub-micrometer resolution from high-harmonic sources via synchrotrons to free-el…

Continuous spectra in high-harmonic generation driven by multicycle laser pulses

We present observations of the emission of XUV continua in the 20-37 eV region by high harmonic generation (HHG) with $4$-$7\ \mathrm{fs}$ pulses focused onto a Kr gas jet. The underlying mechanism relies on coherent control of the relative delays and phases between individually generated attosecond pulse, achievable by adjusting the chirp of the driving pulses and the interaction geometry. Under adequate negative chirp and phase matching conditions, the resulting interpulse interference yields a continuum XUV spectrum, which is due to both microscopic and macroscopic (propagation) contributio…

Micro-focusing of broadband high-order harmonic radiation by a double toroidal mirror

We present an optical system based on two toroidal mirrors in a Wolter configuration to focus broadband XUV radiation. Optimization of the focusing optics alignment is carried out with the aid of an XUV wavefront sensor. Back-propagation of the optimized wavefront to the focus yields a focal spot of 3.6$\times$4.0 $μ$m$^2$ full width at half maximum, which is consistent with ray-tracing simulations that predict a minimum size of 3.0$\times$3.2 $μ$m$^2$. This work is important for optimizing the intensity of focused high-order harmonics in order to reach the nonlinear interaction regime.

通过光波控制的相对论激光等离子体相互作用生成单个阿秒XUV脉冲源：汤姆孙反向散射方案

Single attosecond XUV pulse source via light-wave controlled relativistic laser-plasma interaction: Thomson Back Scattering Scheme

通过优化驱动激光波形生成单个相对论电子层，实现可控的阿秒脉冲源，用于超快现象研究。