Control of the frequency chirp rate of high harmonic pulses

Jens Biegert, ETH Zürich
Mathis Bruck, ETH Zürich
Christoph P. Hauri, ETH Zürich
Arne Heinrich, ETH Zürich
Florian W. Helbing, ETH Zürich
Wouter Kornelis, ETH Zürich
Philip Schlup, ETH Zürich
Ursula Keller, ETH Zürich
Rodrigo López-Martens, Lunds Tekniska Högskola
Johan Mauritsson, Lunds Tekniska Högskola
Per Johnsson, Lunds Tekniska Högskola
Katalin Varjú, Lunds Tekniska Högskola
Anne L'Huillier, Lunds Tekniska Högskola
Mette Gaarde, Louisiana State University
Ken J. Schafer, Louisiana State University


We measured the frequency chirp rate of harmonics 13 to 23 in argon by cross-correlation with a short femtosecond probe pulse. We directly measured the negative chirp due to the atomic dipole phase and demonstrated that an additional chirp on the pump pulse was transferred to the qth harmonic as q times the fundamental chirp.