Abstract
We have measured the far-field angular distributions of high harmonics (orders 11–41) generated by a 1-μm, 1-ps laser pulse [(0.3–3)× W/] in low-density Ar, Kr, and Xe targets (≤1 Torr, 1-mm thick). The far-field harmonic distributions show a narrow central structure surrounded by broad wings that contain approximately 75% of the harmonic energy. Low-density targets and f/70 focusing were used to minimize phase mismatches due to ionization and propagation effects, thereby isolating the single-atom contribution to the response. The wings indicate an intensity-dependent phase of the atomic harmonic emission.
- Received 22 July 1994
DOI:https://doi.org/10.1103/PhysRevA.51.R906
©1995 American Physical Society