J. Phys. IV France
Volume 11, Numéro PR2, Juillet 2001
X-Ray Lasers 2000
Page(s) Pr2-369 - Pr2-372
7th International Conference on X-Ray Lasers

J. Phys. IV France 11 (2001) Pr2-369-Pr2-372

DOI: 10.1051/jp4:2001271

Enhancement of high-order harmonic generation efficiency by double pulse lasers

A. Ishizawa, T. Kanai, T. Ozaki and H. Kuroda

Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan

We have investigated the efficiency of the fifth order harmonics from solid surface plasma by varying the electron density gradient using two 2.2 ps, 1054 nm laser pulses. A prepulse irradiates the Al deposited target 0-20 ps prior to the arrival of the main Nd : Glass laser pulse in order to modify the electron density gradient. It is found that 5 ps time difference between the prepulse and main pulse results in an increase in the third harmonic signal by a factor of 2-3, which then decreases for time delays greater than 10 ps, and the fourth and fifth harmonic signal also increase. Experiments and calculations are presented that demonstrate a strong dependence of the conversion efficiency on the plasma scale length.

© EDP Sciences 2001