Spectral interference of attosecond light pulses

Attosecond pulses can be produced by using the process of high-order harmonic generation in noble gases [1]. Few-cycle driving pulses allow one to confine the emission process to a Single optical cycle so that single X-ray sub-femtosecond pulses can be generated [2],[3]. In the case of multicycle driving pulses, trains of attosecond pulses are produced [1],[4],[5]. Recently, it has been demonstrated that the use of driving pulses with stable carrier-envelope phase (CEP) allows one to control the spectral distribution of the soft X-ray radiation generated by few-cycle infrared (IR) pulses [6]. From both a fundamental and a technical point of view, it is essential to understand the CEP effects on the phase of the harmonics and on the electric-field evolution of the attosecond pulses. © 2007 Springer-Verlag New York.