Enhancement of HHG by varying the CEP shift

2013-07-05T00:00:00Z (GMT) by Di Zhao Fu-li Li Shih-I Chu
<p><strong>Figure 3.</strong> Enhancement of HHG by varying the CEP shift. The intensity of the cavity-mode field is 1 <b>×</b> 10<sup>8</sup> W cm<sup>−2</sup>. Other parameters are the same as those in figure <a href="http://iopscience.iop.org/0953-4075/46/14/145403/article#jpb464914f1" target="_blank">1</a>. For clarity, HHG peaks of the comb structure are connected by a line.</p> <p><strong>Abstract</strong></p> <p>We present a theoretical investigation of the multiphoton resonance dynamics driven by intense frequency-comb and cavity-mode fields inside a femtosecond enhancement cavity (fsEC). The many-mode Floquet theorem is employed to provide a nonperturbative and exact treatment of the interaction between a quantum system and laser fields. The quasienergy structure driven by the frequency-comb laser field is modified by coupling the cavity-mode field and the multiphoton resonance processes between modified quasienergy states, resulting in the generation of even-order harmonics. The high-order harmonic generation (HHG) from a two-level system driven by the laser fields can be coherently controlled by tuning the laser parameters. In particular, the tuning intensity of the cavity-mode field allows one to coherently control the HHG power spectra without changing the absolute positions of comb frequencies.</p>