Spatial Distribution of High Order Harmonics Generated in the Tunneling Regime

Abstract

Production of laser harmonics occurs when a high-intensity laser interacts with a non-linear medium. At sufficiently high intensities any medium will show non-linear effects. We have observed high-order odd harmonic generation using a l-µm, 1-ps laser pulse at intensities between 1013 and 1016 W/cm2, and we have measured the spatial profiles of the harmonics. The existence of high order odd harmonics has previously been demonstrated1 in noble gases using intensities between 1013 and 1014 W/cm2.