High-order harmonic generation by atoms with strong high-frequency and low-frequency pumping

Tafanukhin, VI Shubin, NY

Vi. Tafanukhin et Ny. Shubin, High-order harmonic generation by atoms with strong high-frequency and low-frequency pumping, J OPT SOC B, 17(9), 2000, pp. 1509-1516

22

INGLESE

Article

Apllied Physucs/Condensed Matter/Materiales Science","Optics & Acoustics

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS

0740-3224 → ACNP

17

9

2000

1509 - 1516

ISI

0740-3224(200009)17:9<1509:HHGBAW>2.0.ZU;2-D

We propose to use a low-frequency radiation in addition to the basic pump t o enhance the efficiency of high-order harmonic generation following atom t unnel above-threshold ionization. This enhancement can be achieved without an increase of basic pump intensity and, consequently, without additional s aturation of ionization. A static field added to the basic pump modifies ph otoelectron trajectories in the continuum that leads to a high-frequency ex tension of harmonic spectrum. This is caused by an increase in the part of recombining photoelectrons, kinetic energy of such electrons, and recombina tion efficiency towing to reduced electron wave-packet spreading). An exper imental realization of this effect is proposed with use of the radiation of a powerful CO2 laser and ultrashort basic pump pulses. It is shown that th e maximum-generated frequency can be tripled with this technique. Also, a m ultiplateau structure of the high-frequency region of the harmonic spectrum has been revealed and explained. (C) 2000 Optical Society of America [S074 0-3224(00)01308-4].