Many-mode Floquet theoretical approach for coherent control of multiphoton dynamics driven by intense frequency-comb laser fields

Abstract

We extend the many-mode Floquet theorem (MMFT) for the investigation of multiphoton resonance dynamics driven by intense frequency-comb laser fields. The frequency comb structure generated by a train of short laser pulses can be exactly represented by a combination of the main frequency and the repetition frequency. MMFT allows non-perturbative and exact treatment of the interaction of a quantum system with the frequency-comb laser fields. We observe simultaneous multiphoton resonance processes between a two-level system and frequency-comb laser. The multiphoton processes can be coherently controlled by tuning the laser parameters such as the carrier-envelope phase (CEP) shift. In particular, high-order harmonic generation shows immense enhancement by tuning the CEP shift, due to simultaneous multiphoton resonances. © 2008 The American Physical Society.