(a) Quasienergies and (b) time-averaged transition probabilities as a function of the intensity of the cavity-mode field

2013-07-05T00:00:00Z (GMT) by Di Zhao Fu-li Li Shih-I Chu
<p><strong>Figure 4.</strong> (a) Quasienergies and (b) time-averaged transition probabilities as a function of the intensity of the cavity-mode field. The resonance position is at 1.489 <b>×</b> 10<sup>11</sup> W cm<sup>−2</sup>. (c) The enhancement of HHG power spectra by tuning the intensity of the cavity-mode field. For clarity, HHG peaks of the comb structure are connected by a line. The energy separation is fixed at ω<sub>αβ</sub> = 0.17 au. The CEP shift is fixed at Δ = 0.4385 <b>×</b> 2π. The parameters of the frequency-comb field are peak intensity 1 <b>×</b> 10<sup>14</sup> W cm<sup>−2</sup>, carrier frequency 563.5 THz and repetition frequency 10 THz of 20 fs FWHM Gaussian pulses. The carrier frequency of the cavity-mode field is 10 THz.</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>