Distinction in resonance properties of the atomic and molecular contained plasmas used for high-order harmonics generation of ultrafast laser pulses
Аннотация
The mechanism of resonance enhancement of a single harmonic during high-order harmonic generation in indium-, zinc-, and chromium-contained atomic and molecular plasmas is reexamined using single-color and two-color pumps of ablated species. We demonstrate that oxides, selenides, and phosphides of these metals notably reduce the enhancement of a single harmonic compared with purely atomic plasma due to either a shift of the ionic transitions possessing strong oscillator strength out of the wavelength of those harmonics or a reduction of the oscillator strength of these transitions. The role of oscillator strength in harmonic enhancement is discussed and compared with improvements in phase-matching conditions for some harmonics in the region of anomalous dispersion of ionic transitions. The application of different wavelengths of driving pulses drastically changes the enhancement of a single harmonic in indium-contained plasmas.