Control of High Harmonic Generation with a Second Beam

Abstract

We report the use of a second beam to vary the phase-matching condition of high harmonic generation in a semi- infinitive gas cell. The phase-matching can be improved or destroyed by the second beam. The enhancement of the phase-matching at high ionization rate with a second beam can be used to extend the cut-off photon energy in an atomic or molecular gas. The second beam with different carrier frequency can be used for the generation of continuous XUV spectra. In a molecular gas the second beam creates a vibrational and rotational wave packet which leads to a modulation of the HHG intensity and can be used to study the molecular structure