On the effects of strong ionization in medium-order harmonic generation

Year: 2002

Authors: Bellini M., Corsi C., Gambino M.C.

Autors Affiliation: Inst Nazl Ott Applicata, I-50125 Florence, Italy
European Lab Non Linear Spect, I-50125 Florence, Italy; INFM, I-50125 Florence, Italy; Univ Florence, Dept Phys, I-50125 Florence, Italy

Abstract: Strong ionization of the gas medium has significant effects in the process of medium-order harmonic generation. The combined effect of neutral atom depletion and defocusing of the pump beam due to the intensity-dependent density of free electrons, significantly modifies the conversion characteristics and efficiency. For moderate harmonic orders, the yield is optimized for well-defined values of the pump laser intensity that do not depend on the order or on the focusing geometry, but only on the ionization potential of the gas. In particular focusing conditions, the ionization-induced defocusing can effectively guide the pump beam along channels of optimum intensity, thus enhancing the overall conversion efficiency. We demonstrate that a very simple model is able to reproduce all our experimental results in a surprisingly good way.

Journal/Review: LASER AND PARTICLE BEAMS

Volume: 20 (2)      Pages from: 277  to: 284

KeyWords: Beam propagation; High-order harmonic generation; Strong-field ionization; Ultrashort laser pulses; Electrons; Ionization of gases; Particle beams; Pumping (laser)
DOI: 10.1017/S0263034602202189

Citations: 9
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