Generation of circularly polarized multiple high-order harmonic emission from two-color crossed laser beams

We present a scheme for the production of circularly polarized multiple high-order harmonic generation (HHG). The proposed experimental setup involves,the use of two-color laser fields, consisting of a circularly polarized fundamental laser field and a linearly polarized second-harmonic laser field, in crossed-beam configuration. The feasibility of such a scheme is demonstrated by an nb initio quantal study of the HHG power spectrum of He atoms by means of the time-dependent density-functional theory with optimized effective potential and self-interaction correction recently developed. The theoretical study also provides insights regarding the different mechanisms responsible for the production of HHG in different energy regimes as well as the mechanism for the generation of continuous background radiation. [S1050-2947(98)50410-6].