THEORY OF HIGH-ORDER HARMONIC-GENERATION BY AN ELLIPTICALLY POLARIZEDLASER FIELD

We generalize a recently formulated theory of high-order harmonic gene ration by low-frequency laser fields [Anne L'Huillier et al., Phys. Re v. A 48, R3433 (1993)] to the case of an elliptically polarized light. Our theoretical description includes both the single-atom response an d propagation. Phase matching significantly modifies the results obtai ned in the single-atom response. The results of our calculations, incl uding propagation for both the intensity and polarization properties o f harmonics as a function of laser ellipticity, compare very well with recent experimental observations.