High-order harmonics and xuv spectroscopy
We deal with laser-matter interactions at very high intensities.
One of our main activities over the last years has been the production of coherent radiation in the extreme ultraviolet (XUV) by high-order harmonic generation. Fundamental studies are performed concerning the generation process itself, with the detailed analysis of the contribution of the electronic dynamics to the production of different harmonic orders. New schemes based on quasi-phase-matching are also being developed to enhance the conversion efficiency.
Concerning the applications of this new source, a novel Ramsey technique developed at INO is used for spectroscopy of bound and auto-ionizing atomic transitions in the XUV. The resolution limits of such approach are being tested and new schemes, based on random delay sampling, have led to absolute XUV frequency measurements.
A novel Ramsey split-pulse configuration has recently realized, based on a widely-unbalanced and accurately-stabilized Michelson interferometer placed under vacuum conditions. The system has been used for the characterization of the pulse-to-pulse phase stability of a metrological IR laser comb.
Other applications of our harmonic source concern the use of the linearly-polarized XUV radiation as a test source for space optics and detectors.