Lay summary
Short-wavelength sources, i.e. 10-50 nm (Extreme Ultraviolet) or 0.1-10 nm (soft X-rays), are enabling for a number of cutting-edge investigations such as in materials, nano/bio-imaging/spectrometry, and molecular/atomic physics. Brightness and coherence, along with wavelength tunability, are crucial source performance factors in this respect. Accelerator-based facilities, e.g. synchrotrons, xFELs, represent state-of-the-art short wavelength sources. These are however bottlenecked in terms of user accessibility and out of the plans of the industry due to their high cost-of-ownership.

The generation of hot and dense laser micro-plasmas presents the appeal of combining source performance with compactness. Laboratory-scale XUV sources are obtained either by high-harmonic generation (HHG) of an intense laser pulse in a gas jet, or by amplified spontaneous emission (ASE) across a laser-plasma column. The former leads to a broad-band spectrum that is thus utilized for femto/atto-second pulse generation, i.e. fast time-resolved diagnostics. ASE, on the other hand, leads to ultra-narrow linewidths that are thus ideal for imaging or high-resolution spectroscopy.

 The "BeAGLE" (Bern Advanced Glass Laser for Experiment) facility is a worldwide unique facility, which has demonstrated the shortest ASE wavelengths in a single-beam laboratory setup. In order to fully exploit the XUV laser characteristics, fundamental research is performed  to address issues on the in-band output and repetition rate. The former is originally attempted by investigation of cavity targets that will waveguide the ASE gain across the plasma column, thus mitigating refractive losses. The single-shot operation will be scaled-up to Hz-level exploiding an optical parametric (OP) and chirped pulse amplification (CPA) architecture.

These fundamental-science contributions have immediate implementation in actinic
("at-wavelengh") nano-imaging and surface spectroscopy. The former is crucial for enabling manufacturing of next generation integrated circuits (ICs). High volume manufacturing of sub-32-nm ICs using EUV light by means of photo-lithography, requires that the mask is a fully defect-free template. Actinic inspection at nano-scale level is possible only if laboratory at-wavelength sources are demonstrated. The combination of nano-imaging and nano-spectroscopy will lead to an integrated lab-scale morpho-chemical mapping tool.

This research program is composed of three main modules: LAPLAS (laser plasma source fundamentals), ACTINIC (nano-imaging using XUV coherent light), XULPES (XUV photoelectron spectroscopy and PEEM). Domestic and international collaboration on strategic aspects is functional to complement the portfolio of competences.