Colloquium on August 15th, 2005

Pierre Agostini
CEA Saclay, France

High harmonics attosecond chirp

Atoms excited by a strong infrared field emit a wide spectrum of high harmonics. On an attosecond time scale the physics of the emission entails that it actually occurs as ultrashort flashes twice per optical cycle of the pump field. This talk will describe the characterization of the harmonics spectral phase which reveals that all the harmonics are not emitted simultaneously but with a time delay proportional to the order. The consequences on the ultimate duration of the attosecond pulses will be discussed.