When atoms interact with strong laser fields, high-order harmonics are generated. In the time domain, this radiation consists of ultrashort "attosecond" light pulses with central photon energy in the extreme ultraviolet (XUV) energy domain and duration of the order of 100 as.
Attosecond science consists in generating attosecond pulses and in using them to study ultrafast dynamics. The time scale is that of the electron motion in atoms, molecules or more complex systems. Temporal information can be obtained either by pump-probe techniques or by phase and amplitude measurements over a large spectral range. The pump-probe technique uses a pump pulse to excite the system, a probe pulse to analyze it, and the delay between the pump and probe pulses is varied.
Attosecond science requires a scientific environment combining at the same time:
- State-of-the-art ultrafast laser technology
- Advanced attosecond engineering
- A strong application program
Our research is attacking all three areas at the same time. Applications demand certain specifications: for example single attosecond pulses, high pulse energy, high repetition rate or certain photon energy. These specifications require specific ultrafast laser technology as well as attosecond engineering in order to produce the needed attosecond source. We explore applications in a large variety of areas, from atomic and molecular physics, to surface physics, plasmonics and ultrafast coherent imaging.