A Near Fourier-Limited Pulse-Preserving Monochromator for Extreme-Ultraviolet Pulses in the Few-Fs Regime

We present a pulse-preserving multilayer-based extreme-ultraviolet (XUV) monochromator providing ultra-narrow bandwidth (Δ𝐸<0.6eV, 𝐸c=92eV) and compact footprint (28×10cm2) for easy integration into high-harmonic generation (HHG) or free-electron laser (FEL) sources. The temporal resolution of the novel design supports pulse durations of typical pump–probe setups in the femtosecond and attosecond regime, depending on the mirror design and focusing geometries over the tuning range of the monochromator. The theoretical design is analyzed and experimentally characterized in a laser-driven HHG setup.