Generation of exceptionally strong harmonics from he in an orthogonally polarized two-color laser field

Abstract

Highly efficient high-harmonic generation was achieved using a two-color laser field that consisted of the fundamental and its second harmonic. The harmonics generated in an orthogonally polarized two-color field were stronger than those obtained in the fundamental field by more than two orders of magnitude. Conversion efficiency as high as 5 × 10 was obtained for the 38th harmonic (21.6 nm) from helium driven by the two-color laser field with a proper relative phase. This enhancement is explained by analyzing the electron behavior in the two-color field. In addition, we confirmed the effects of mixed field by controlling the time delay between the two-color laser fields. © 2007 Springer-Verlag New York.