Coherent Focusing of High Harmonics: A New Way Towards the Extreme Intensities
Abstract
We demonstrate analytically and numerically that focusing of high harmonics produced by the reflection of a few-femtosecond laser pulse from a concave plasma surface opens a new way to unprecedentally high intensities. The key features allowing the boosting of the focal intensity are the harmonics coherency and the small exponent of the power-law decay of the harmonics spectrum. Using similarity theory and direct particle-in-cell simulations, we find that the intensity at the focus scales as ICHF∝a30I0, where a0 and I0∝a20 are the dimensionless relativistic amplitude and the intensity of the incident laser pulse. The scaling suggests that due to the coherent harmonic focusing (CHF), the Schwinger intensity limit can be reached using lasers with I0≈1022 W/cm2. The pulse duration at the focus scales as τCHF∝1/a20 and reaches the subattosecond range.
- Publication:
-
Physical Review Letters
- Pub Date:
- March 2005
- DOI:
- 10.1103/PhysRevLett.94.103903
- Bibcode:
- 2005PhRvL..94j3903G
- Keywords:
-
- 42.65.Ky;
- 03.50.De;
- 42.65.Re;
- Frequency conversion;
- harmonic generation including higher-order harmonic generation;
- Classical electromagnetism Maxwell equations;
- Ultrafast processes;
- optical pulse generation and pulse compression