Multi-µJ coherent extreme ultraviolet source generated from carbon using the plasma harmonic method.
We demonstrate intense high-order harmonic generation from plasma that is created from different carbon targets. We obtain high-order harmonic energy in the multi-microjoule range for each harmonic order from the 11th to the 17th harmonic. By analyzing the target morphology and the plasma composition, we conclude that the intense harmonics from the bulk carbon targets originate from nanoparticles target.
Time resolved spectroscopy of laser induced graphite plasma relevant to high-order harmonic generation
We perform spectroscopic characterization of graphite plasma to study the species responsible for high-order harmonics generation. We observed that visible region contains vibrational transitions of C2 and C3 molecules. Under the same conditions, we found shorter delays are favorable for intense HHG.
Quasi-phase matching of high-harmonics and attosecond pulses in modulated waveguides.
We describe theoretically a new technique for quasi-phase-matched generation of high harmonics and attosecond pulses in a gas medium, in a high ionization limit. A corrugated hollow-core fiber modulates the intensity of the fundamental pulse along the direction of propagation, resulting in a periodic modulation of the harmonic emission at wavelengths close to the cutoff. This leads to an increase of the harmonic yield of up to three orders of magnitude. At the same time the highest harmonics merge in a broad band that corresponds to a single attosecond pulse, using 15-fs driving pulses.