High Harmonic Generation at Long Wavelengths

Abstract

High harmonic radiation spectra up to 19th order in alkali metal vapors excited by an intense, picosecond mid-infrared ( $3--4\ensuremath{\mu}\mathrm{m}$) laser are reported and compared to theory. The strong-field dynamics in the alkali metal atoms exhibit significant differences from all previously studied systems due to the strong coupling between their ground and first excited states.