ABSTRACT
The advent of subfemtosecond or attosecond light pulses will open new fields of extreme nonlinear optics. Recently, experimental results on the production and measurement of a single 250-asec pulse were reported by Krausz et al [1]. This opens up new possibilities for studying and controlling electron dynamics in atoms and molecules in asee time scale. Recently, Drescher et.al [2] has demonstrated that a laser-based sampling system, consisting of a few-femtosecond visible light pulse and a asynchronized sub-femtosecond soft X-ray pulse, allows us to trace the relaxation dynamics directly in the time domain with attosecond resolution. Moreover, photoionization and high-order harmonic generation (HHG) in molecular systems under the action of combined infrared femtosecond and ultraviolet attosecond laser pulses were investigated by Bandrauk and Shon [3]. It was shown that punctual "turn-on" of an asee pulse can trigger the ionization process, which in turn leads to significant enhancement of HHG. Despite the extensive work in this area, propagation of subfemtosecond laser pulse has rarely been investigated.
