J. Phys. IV France 11 (2001) Pr2-339-Pr2-344
Optimization of conversion efficiency and spatial quality of high-order harmonic generationK. Midorikawa1, Y. Tamaki2, J. Itatani1 and M. Obara2
1 Laser Technology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
2 Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
Optimization of high-order harmonic generation has been studied with a 30 fs laser at an intensity of < 2x10 14 W/cm2 in a quasi-static gas cell ([MATH]) filled with argon ([MATH]). The effect of propagation length and gas density on the conversion efficiency and spatial quality of high-order harmonics are investigated comprehensively. As a result of phase-matched propagation, both the spatial quality and conversion efficiency of the 29th harmonic are successfully optimized to Gaussian-like profile with a divergence of 4.5 mrad (full width at l/e2 maximum) and a saturated efficiency. A quasi-two-dimensional simulation confirms the phasematching effect.
© EDP Sciences 2001