G. Steinmeyer, D.H. Sutter, L. Gallmann and U. Keller, Swiss Federal Institute of Technology, Zurich
The 1999 Nobel Prize in chemistry rewarded not only Ahmed Zewail's pioneering work on ultrafast spectroscopy and femtochemistry, but also the entire field of ultrafast optics and femtosecond laser applications. In the last decade, pulse durations have shrunk from the 40 to 60 fs that Zewail used to below two optical cycles, corresponding to about 5 fs in the visible/near-infrared spectral region.
With these extremely short pulses, we can begin to reach a novel regime of light/matter interaction, which some authors call "extreme nonlinear optics." So far, reductions in laser pulse duration have incrementally affected traditional ultrafast laser applications: We can measure a 200-fs chemical reaction with a 20-fs or a 5-fs pulse. As pulse durations in the two-cycle regime become more accessible, however, new applications open up. This regime of extreme nonlinear optics and attosecond science will make ultrafast lasers a hot topic for years.